FAIZ UL ISLAM

Category: class 9th notes

  • 9th Class Physics Chapter 9: Transfer of Heat

    9th Class Chapter 9: Transfer of Heat Short and Simple Question & Answer

    On this page, you will find the Physics Estimate Paper for Class 9 for the year 2024, available in both English and Urdu. We offer two formats for downloading the most important questions for Class 9 Physics. This estimate paper is suitable for all boards in Punjab, including BISE boards in Faisalabad, Lahore, Gujranwala, Dera Ghazi Khan, Sargodha, Sahiwal, Multan, and Jammu Kashmir. Many students have successfully used the Physics Estimate Paper 2024 by Faiz Ul Islam to achieve good results in their exams.

    Q1.How many method of transmission of heat are used?

    Ans: Heat can be transmitted from one object to the other by the following three processes, if these objects are at different temperatures.

    • Conduction
    • Convection
    • Radiation

    Q2.What is Conduction? Explain the process and write down it usage in our daily life.

    Ans: “The mode of transfer of heat by vibrating atoms and free electrons in solids from hot to cold parts of a body is called conduction of heat”.

    OR

    “Conduction is the process in which heat is transmitted from one body to another by the interaction of atoms and electrons”.

    Q3.What are Bad conductors or Insulator?

    Ans: The substances through which heat does not conduct easily are called bad conductors or insulators.

    Example

    Wood, cork, cotton, wool, glass, rubber etc.

    Q4.What are Conductors?

    Ans: All metals are good conductors of heat. The substances through which heat conduct easily are called conductors.

    Example

    Copper, iron, aluminum etc.

    Q5.Write down some uses of conductors and non – conductors.

    Ans: In houses, good thermal insulation means lower consumption of fuel. For this, following measures may be taken to save energy.

    • Hot water tanks are insulated by plastic or foam lagging
    • Ceiling of room is covered by insulating materials (false ceiling)
    • Good conductors are used when quick transfer of heat is required through a body. Thus cookers, cooking plate, boiler, radiators and condensers of refrigerators etc. are made of metals such as aluminum or copper. Similarly metal boxes are used for making ice, ice cream etc.

    Q6.Define convection?

    Ans: “Transfer of heat by actual movement of molecules from hot place to a cold place is known as convection”.

    Liquids and gases are poor conductors of heat. However, heat is transferred through fluids (liquids or gases) by another method called convection.

    Q7.What do you know about convection currents in Air? Write down some uses.

    Ans:  Gases also expand on heating, thus convection currents are easily set up due to the differences in the densities of air at various parts in the atmosphere.

    Uses of Convection currents

    • Convection currents set up by electric, gas or coal heaters help to warm our homes and offices.
    • Central heating systems in buildings work on the same principle of convection.

    Q8.How land and sea breezes are produced?

    Ans: Land and sea breezes are the result of convection.

    Sea Breeze

    On a hot day, the temperature of the land increases more quickly than the sea. It is because the specific heat of land is much smaller as compared to water. The air above land gets hot and rises up. Cold air from the sea begins to move towards the land. It is called sea breeze.

    Land Breeze

    At night, the land cools faster than the sea. Therefore, air above the sea is warmer, rises up and the cold air from the land begins to move towards the sea. It is called land breeze.

    Q9.What is gliding?

    Ans: A glider looks like a small aeroplane without engine. Glider pilots use upward movement of hot air current due to convection of heat. These rising currents of hot air are called thermals. Gliders ride over these thermals. The upward movement of air currents in thermals helps them to stay in air for a long period.

    Q10.What do you know about birds gliding?

    Ans: The birds stretch out their wings and circle in these thermals. The upward movement of air helps birds to climb up with it. Eagles, hawks and vultures are expert thermal climbers. After getting a free lift, birds are able to fly for hours without flapping their wings. They glide from one thermal to another, and thus travel through large distances and hardly need to flap their wings.

    Q11.Define Radiation.

    Ans: Radiation is the mode of transfer of heat from one place to another in the form of waves called Electromagnetic waves.

    Q12.Why tea in a cup becomes cold earlier as compared to a teapot?

    Ans: In a teapot there is a large amount of tea and also the mouth of the teapot is narrow, so loss of heat is minimum. On the other hand in a tea cup, there is little amount of tea and the mouth of cup is also large as compared to teapot. Since, larer the surface area, greater will be the heat loss by convection. That is why tea in a cup becomes cold earlier as compare to teapot.

    Download PDF Format

    When preparing for their final exams, students can utilize the 9th-grade Physics assessment paper. Every chapter from the textbook is covered, along with questions that may appear on the exam. These essential questions serve as valuable study aids after students have completed the entire syllabus. By focusing on these key concepts, students can gauge their understanding and boost their confidence, ultimately enhancing their exam performance.

    Class 9 Physics Estimate Paper 2024 for Punjab Board Students

    Physics is often considered a challenging subject. The exam date for Class 9 Physics papers has been released, with all Punjab Boards conducting these papers on Friday. With limited time for preparation, using these important questions can significantly aid in covering the essential topics.

    Additionally, these questions will enhance your knowledge and help you prepare for the crucial questions expected in the exams. One of the standout features of our estimate paper is that it can be downloaded for free, allowing you to print these important questions at no cost.

  • 9th Class Physics Chapter 8: Thermal Properties of Matter

    9th Class Chapter 8: Thermal Properties of Matter Short and Simple Question & Answer

    On this page, you will find the Physics Estimate Paper for Class 9 for the year 2024, available in both English and Urdu. We offer two formats for downloading the most important questions for Class 9 Physics. This estimate paper is suitable for all boards in Punjab, including BISE boards in Faisalabad, Lahore, Gujranwala, Dera Ghazi Khan, Sargodha, Sahiwal, Multan, and Jammu Kashmir. Many students have successfully used the Physics Estimate Paper 2024 by Faiz Ul Islam to achieve good results in their exams.

    Q1.Define heat.

    Ans: Heat is the energy that is transferred from one body to the other in thermal contact with each other as a result of the difference of temperature.

    Q2.Define thermometry and temperature.

    Ans:   

    Thermometry

    “The art of measuring temperature is termed as thermometry.”

    Temperature

    “Degree of coldness or hotness of the body is a measure of its temperature”

    Q3.Define internal energy.

    Ans: The sum of kinetic energy and potential energy associated with the atoms, molecules and particles of a body is called the internal energy.

    Q4.Define thermal equilibrium.

    Ans: “According to the principle of thermometry, if two objects at different temperatures are joined together, after a certain time they attain the same temperature. This is known as the state of thermal equilibrium”

    Q5.Define thermometer.

    Ans: “The instrument which is used to measure the temperature is called a thermometer”

    Q6.Write down the conversions of thermometer scales.

    Ans: Conversion of one temperature scale to the other by the given formulae TF, Tc, TK representing the Fahrenheit, centigrade (Celsius) and Kelvin temperatures respectively.

    Conversion of Celsius (centigrade) to Fahrenheit scale

    TF =

    Conversion of Fahrenheit to Celsius scale

    Tc =

    Relationship between Kelvin and Celsius scales

    Tk = Tc + 273

    Q7.Define specific heat?

    Ans: “Specific heat of a substance is the amount of heat that required to raise the temperature of 1 kg mass of that substance through 1K”.

    Q8.Define heat capacity.

    Ans: Heat capacity of a body is the quantity of thermal energy absorbed by it for one Kelvin (1K) increases in its temperature.

    Q9.Define latent heat of fusion.

    Ans: “Heat energy required to change unit mass of a substance from solid to liquid state at its melting point without change in the temperature is called its latent heat of fusion”.

    Q10.Define latent heat of vaporization.

    Ans: “The quantity of heat that changes unit mass of a liquid completely into gas at its boiling point without any change in its temperature is called its latent heat of vaporization”

    Q11.Define evaporation.

    Ans: “Evaporation is the changing of a liquid into vapors (gaseous state) from the surface of the liquid without heating it”.

    Q12.What is linear Expansion?

    Ans:  “If a thin rod is heated, there is a prominent increase in its length as compared to its cross-sectional area. The expansion along length or in one dimension is called linear expansion”.

    Q13.What is volume expansion?

    Ans: “Heating a block causes an increase in length, breadth and thickness, i.e., volume of the block increases that is known as volume expansion”.

    Volume of a solid also changes with the change in temperature and is called volume thermal expansion or cubical thermal expansion.

    Q14.Write down some consequences of thermal expansion.

    Ans:  The expansions of solids many damage bridges, railway tracks and roads as they are constantly subjected to temperature changes.

    • Prevision is made during construction for expansion and contraction with temperature.
    • Railway tracks buckled on a hot summer day due to expansion if gaps are not left between sections.

    Q15.Write down some applications of thermal expansion.

    Ans: Thermal expansion is used in our daily life. In thermometers, thermal expansion is used in temperature measurements.

    • To open the cap of a bottle that is tight enough, immerse it in hot water for a minute or so. Metal cap expands and becomes loose. It would now be easy to turn it to open.
    • To join steel plates tightly together, red hot rivets are forced through holes in the plates as shown in figure. The end of hot rivet is then hammered. On cooling, the rivets contracts and bring the plates tightly griped.

    Q16.What do you know about bimetallic strip (thermostat)?

    Ans: A bimetal strip consists of two thin strips of different metals such as brass and iron joined together as shown in figure. On heating the strip, brass expands more than iron. This unequal expansion causes bending of the strip.

    Usage

    Bimetal strips are used for various purposes.

    • Bimetal thermometers are used to measure temperature especially in furnaces and ovens.
    • Bimetal thermo state switch is used to control the temperature of heater coil in an electric iron.

    Q17.Write down some examples of expansions of solids.

    Ans:

    • Pipes passing through deserts and plains are curved to allow expansion and contraction due to change of season.
    • While laying rail tracks gaps are left at joints so as to avoid damages caused by expansion or contraction.
    • While constructing bridges, one end of the beam is placed on rollers. Explain why?

    Ans: This is because the iron beam of the bridges expands due to heat in summer. The iron beams are frightened at one end, keeping the other moveable as provision for their expansion. In the absence of such provision, bridge may be damaged in summer due to heat.

    Download PDF Format

    When preparing for their final exams, students can utilize the 9th-grade Physics assessment paper. Every chapter from the textbook is covered, along with questions that may appear on the exam. These essential questions serve as valuable study aids after students have completed the entire syllabus. By focusing on these key concepts, students can gauge their understanding and boost their confidence, ultimately enhancing their exam performance.

    Class 9 Physics Estimate Paper 2024 for Punjab Board Students

    Physics is often considered a challenging subject. The exam date for Class 9 Physics papers has been released, with all Punjab Boards conducting these papers on Friday. With limited time for preparation, using these important questions can significantly aid in covering the essential topics.

    Additionally, these questions will enhance your knowledge and help you prepare for the crucial questions expected in the exams. One of the standout features of our estimate paper is that it can be downloaded for free, allowing you to print these important questions at no cost.

  • 9th Class Physics Chapter 7: Properties of Matter

    9th Class Chapter 7: Properties of Matter Short and Simple Question & Answer

    On this page, you will find the Physics Estimate Paper for Class 9 for the year 2024, available in both English and Urdu. We offer two formats for downloading the most important questions for Class 9 Physics. This estimate paper is suitable for all boards in Punjab, including BISE boards in Faisalabad, Lahore, Gujranwala, Dera Ghazi Khan, Sargodha, Sahiwal, Multan, and Jammu Kashmir. Many students have successfully used the Physics Estimate Paper 2024 by Faiz Ul Islam to achieve good results in their exams.

    Q1.What is Kinetic molecular theory? Write down its postulates.

    Ans: Most of the properties of solids, liquids, and gases can be explained on the basis of the intermolecular forces. Kinetic molecular model has some important features.

    • Matter is made up of particles called molecules.
    • The molecules remain in continuous motion. The motion of molecules could be linear, vibrational, or rotational.
    • The molecules attract each other.

    Q2.What is plasma?

    Ans: The kinetic energy of gas molecules goes on increasing if a gas is heated continuously. This causes the gas molecules move faster and faster. The collisions between atoms and molecules of the gas become so strong that they tear off the atoms. Atoms lose their electrons and become positive ions. This ionic state of matter is called plasma.

    Q3,What do you know about density?

    Ans: Density of a substance is defined as its mass per unit volume.

    Unit

    SI unit of density is kilogram per cubic meter (kg m-3).

    Density Equations

    Mass = Density x Volume

    Q4.Define pressure and write down its unit.

    Ans: The force acting normally per unit area on the surface of a body is called pressure.

    Thus

    Or

    Quantity

    Pressure is a scalar quantity.

    Unit

    In SI units, the unit of pressure is N m-2 also called Pascal (Pa). Thus, 1N m-2 = 1Pa

    Q5.Define pressure in liquids.

    Ans: Liquids exert pressure. The pressure of a liquid acts in all directions. If we take pressure sensor (a device that measures pressure) inside a liquid, then the pressure of the liquid varies with the depth of sensor.

    Q6.State Pascal’s Law.

    Ans: Pressure applied at any point of a liquid enclosed in a container, is transmitted without the loss to all other parts of the liquid.

    An external force applied on the surface of a liquid increases the liquid pressure at the surface of the liquid. This increase in liquid pressure is transmitted equally in all direction and to the walls of the container in which it is filled.

    Q7.Explain the braking system of the vehicles.

    Ans: The brakes of cars, buses etc. work on the principle of Pascal’s law. In such a type of brakes, when brake pedal is pushed, it exerts pressure on the master cylinder, which increases the liquid pressure in the cylinder. The liquid pressure is transmitted equally through the liquid in the metal pipes. Due to the increase pressure of the liquid pressure, the pistons in the cylinder mover outwards pressing the brakes pad with brake drums. The force of friction between friction the brake pads and the brake drum stops the wheels.

    Q8.State Archimedes Principle.

    Ans: When object is totally or partially immersed in a liquid, an upthrust act on it equal to the weight of the liquid it displaces.

    Q9.Define principle of floatation

    Ans: A floating object displaces a fluid having weight equal to weight of the object.

    Q10.What is atmospheric pressure?

    Ans: The earth is surrounded by a cover of air is called atmosphere. It extends to a few hundred kilometers above sea level. Just as certain sea creatures live at the bottom of ocean, we live at the bottom of a huge ocean of air. Air is the mixture of gases. The density of air in the atmosphere is not uniform. It decreases continuously as we go up.

    Q11.What is barometer?

    Ans: The instruments that measure atmospheric pressure are called barometers. One of the simple barometers is a mercury barometer. It consists of a glass tube 1 m long closed at one end.

    Q12.Why mercury is used in barometer instead of water?

    Ans: Mercury is 13.6 times denser than water. Atmospheric pressure can hold vertical column of water is about 13.6 times the height of mercury column at a place. Thus, at sea level, vertical height of water column would be 0.76 m x 13.6 = 10.34 m. Thus, a glass tube more than 11 m long is required to make a water barometer.

    Q13.What weather changes can be expected due to decrease of atmospheric pressure?

    Ans:

    • A gradual and average drop in atmospheric pressure means a low pressure in a neighboring locality.
    • Minor but rapid fall in atmosphere indicates a windy and showery condition in the nearby region.
    • A decrease in atmospheric pressure accompanied by breeze and rain.
    • A sudden fall in atmospheric pressure often followed by a storm, rain and typhoon to occur in few hours time.

    Q14.What weather changes can be expected due to increase of atmospheric pressure?

    Ans:

    • An increasing atmospheric pressure with a decline later on predicts an intense weather conditions.
    • A gradual large increase in the atmospheric pressure indicates a long spell of pleasant weather.
    • A rapid increase in atmospheric pressure means that it will soon be followed by a decrease in the atmospheric pressure indicating poor weather ahead.

    Q15.What is Elasticity?

    Ans: The property of a body to restore its original size and shape as the deforming force ceases to act is called elasticity.

    Deforming force

    The applied force that changes shape, length or volume of a substance is called the deforming force.

    Q16.What is stress?

    Ans: The force that acts on unit area at the surface of a body and thus changes its shape or size is called stress.

    Mathematical form

    If a force F is applied on an area A of an object, the stress is) mathematically defined as:

    Unit

    In System International, the unit of stress is Nm-2.

    Q17.What is strain?

    Ans:  A stress can produce a change in shape, length or volume of an object.

    A comparison of change caused by the stress with the original length, volume or shape is called the strain.

    Tensile strain

    If a stress produces a change in length of an object then the stain is called tensile strain. Therefore,

    Unit

    As the strain is a ratio between two similar quantities so it has no unit.

    Q18.Hooke’s Law

    Ans: The strain produced in a body by the stress applied to it is directly proportional to the stress within the elastic limit of the body.

    Mathematical Formula

    Stress α strain

    Stress = constant x strain

    Or         = constant

    Hooke’s law is applicable to all kinds of deformation and all types of matter i.e. solids, liquids or gases within certain limit.

    Q19.Define Young’s Modulus.

    Ans: The ration of stress and strain is a constant within the elastic limit, this constant is called the Young’s Modulus.

    Unit

    SI unit of Young’s Modulus is Newton per square metre (N m-2)

    Q20.What is elastic Limit?

    Ans:  When stress is increased, the strain also goes on increasing until there comes a limit. When stress is removed, the object does not come back to its initial state. This limit of stress is called elastic limit.

    Q21.What are the elastic materials? Give some examples.

    Ans: An object is said to be elastic if it restores its original size and shape after the external force ceases to act. For example rubber, plastic, nylon, iron etc.

    Q22.How property of elasticity is used in our body?

    Ans: Not only metals and other materials are elastic, our body muscles are also elastic. Most of the actions of our body are possible due to expansion and contraction of the muscles.

    Q23.Prove that the SI unit of Young’s modulus is Pascal or Nm-2.

    Ans: Pressure is calculated mathematically as:

    P =  = Nm-2

    Thus, SI unit of pressure is Nm-2 and it is also named as Pascal (pa).

    Q24.Prove that liquid pressure does not depend upon mass of the liquids.

    Ans: Liquid pressure is given by the formula:

    P = ρgh

    Above equation is independent of mass of the liquid. So, liquid pressure does not depend upon the mass of the body.

    Q25.Under what condition the object floats in water?

    Ans: If the buoyant force ‘F’ is greater than the ‘w’ of the immersed object, the resultant force (F – w) will act in the upward direction and it will push the object in upward direction. In this situation, some part of the object will be raised above the water so that the buoyant force ‘F’ becomes equal to the weight. So, equilibrium is established and the object floats.

    Q26.Write any three applications of the Pascal’s law in our daily life.

    Ans:

    • Raw cotton and clothes are pressed to form their bundles for their easy transportation.
    • For the service of heavy vehicles, these are lifted by the use of hydraulic press.
    • The brakes of certain vehicles work on the principle of hydraulic press.

    Q27.When an inflated balloon is heated it bursts. Why?

    Ans: When inflated balloon is heated then motion of the molecules of the gas increases in the balloon and they will increase pressure on the walls of the balloon so it will burst because of this increased gas pressure on it.

    Q28.Under what condition the object sinks in water?

    Ans: If the weight ‘w’ of the immersed object is greater than the buoyant force ‘F’ of the liquid, the resultant force (w – F) will act in the downward direction and the object will sink.

    Download PDF Format

    When preparing for their final exams, students can utilize the 9th-grade Physics assessment paper. Every chapter from the textbook is covered, along with questions that may appear on the exam. These essential questions serve as valuable study aids after students have completed the entire syllabus. By focusing on these key concepts, students can gauge their understanding and boost their confidence, ultimately enhancing their exam performance.

    Class 9 Physics Estimate Paper 2024 for Punjab Board Students

    Physics is often considered a challenging subject. The exam date for Class 9 Physics papers has been released, with all Punjab Boards conducting these papers on Friday. With limited time for preparation, using these important questions can significantly aid in covering the essential topics.

    Additionally, these questions will enhance your knowledge and help you prepare for the crucial questions expected in the exams. One of the standout features of our estimate paper is that it can be downloaded for free, allowing you to print these important questions at no cost.

  • 9th Class Physics Chapter 6: Work and Energy

    9th Class Chapter 6: Work and Energy Short and Simple Question & Answer

    On this page, you will find the Physics Estimate Paper for Class 9 for the year 2024, available in both English and Urdu. We offer two formats for downloading the most important questions for Class 9 Physics. This estimate paper is suitable for all boards in Punjab, including BISE boards in Faisalabad, Lahore, Gujranwala, Dera Ghazi Khan, Sargodha, Sahiwal, Multan, and Jammu Kashmir. Many students have successfully used the Physics Estimate Paper 2024 by Faiz Ul Islam to achieve good results in their exams.

    • Define work and its unit.

    Ans:    Definition

    Work is done when force acting on a body displaces it in the direction of a force.

    OR

    The product of force and distance covered in the direction of force is equal to the work done.

    Unit of work

    In System International, its unit is joule (J).

    Joule

    “The amount of Work done will be one joule if a force of one Newton displaces a body through a distance of one meter in the direction of the force.”

    • Define Energy and write down its unit. 

    Ans: A body possesses energy if it is capable to do work.

    OR

    Ability of a body to do work is known as energy.

    Quantity

    It is a scalar quantity

    Unit

    Joule is the unit of energy same as that of work.

    Types of Energy

    Energy exists in various forms such as mechanical energy, heat energy, light energy, sound energy, electrical energy, chemical energy and nuclear energy etc.

    Types of Mechanical Energy

    Mechanical energy possessed by a body is of two types:

    • Kinetic Energy
    • Potential Energy
    • Define kinetic energy and give at least one example.

    Ans: “The energy possessed by a body due to its motion is called kinetic energy”

    Example

    • Moving water in a river can carry wooden logs through large distances and can also be used to drive turbines for generating electricity.
    • Define Potential Energy and give examples.

    Ans: The energy possessed by a body due to its position is known as its potential energy.

    Examples

    • Stored water in dam
    • A hammer is raised up to some height has the ability to do work
    • A stretched bow has potential energy due to its stretched
    • Define Gravitational Potential Energy and give at least one example.

    Ans: The energy present in a body due to its height is called gravitational potential energy.

    Example

    • Stored water in dam
    • Energy of a stone lying on the roof
    • Define Efficiency.   

    Ans: Efficiency of a system is the ratio of required form of energy obtained from a system as output to the total energy given to it as input.

    • What do you know about Ideal machine?

    Ans: An ideal machine is that which gives an output equal to the total energy used by it. In other words, its efficiency is 100 %. People have tried to design a working system that would be 100% efficient. But practically such system does not exist.

    • Can we say that practical systems can be 100% efficient?

    Ans: Every system meets energy losses due to friction that causes heat, noise etc. these are not the useful forms of energy and go waste. This means we cannot utilize all the energy given to working system. The energy in the required form obtained from working system always less than the energy given to it as input.

    • Define Power. Write down its unit and define it.

    Ans: “Rate of doing work with respect to time is called the power.”

    Unit of power

    In System International, the unit of power is watt (W).

    Watt

    “If a body does a work of one joule in one second then its power will be one watt”.

    • Do we do any work when we lift a load from the Earth to some height?

    Ans: Yes, we do work when we lift a load from the earth to some height because we have to do work against the gravitational pull of the earth. Mathematically, it can be expressed as,

    As we know that                     W = FS

    As        F = mg             and       S = h

    So the work done is                W = mgh

    • How much power is used by a 40 kg athlete by climbing 10m high ladder in 10s?

    Ans:   

    We have                      Mass = m = 40 kg

    Time = t = 10 s

    Height = h = S = 10 m

    As we know that         Force = weight = w = mg = 40 x 10 = 400N

    Work = W = FS = 400 x 10 = 4000 J

    As we know that         Power = P = W/t

    So,                               Power = P = 4000/10 = 400 W

    • Give some examples of energies used in our body?

    Ans:  There are many kinds of energies are used in our body. Some of them are given below:

    Mechanical Energy

    For the moving of our body.

    Chemical Energy

    For making body molecules.

    Electrical Energy

    For the propagation of electrical signals in the body.

    Heat Energy

    For maintaining the body temperature.

    • How much work is done when a body moves with uniform velocity?

    Ans: When a body moves with uniform velocity means moving with zero acceleration then work done will be zero because according to Newton’s second law of motion if a = 0 then the net resultant force acting on the body is zero.

    As we know that                                 W = FS

    If         F = 0                 then                W = 0 x S = 0

    Download PDF Format

    When preparing for their final exams, students can utilize the 9th-grade Physics assessment paper. Every chapter from the textbook is covered, along with questions that may appear on the exam. These essential questions serve as valuable study aids after students have completed the entire syllabus. By focusing on these key concepts, students can gauge their understanding and boost their confidence, ultimately enhancing their exam performance.

    Class 9 Physics Estimate Paper 2024 for Punjab Board Students

    Physics is often considered a challenging subject. The exam date for Class 9 Physics papers has been released, with all Punjab Boards conducting these papers on Friday. With limited time for preparation, using these important questions can significantly aid in covering the essential topics.

    Additionally, these questions will enhance your knowledge and help you prepare for the crucial questions expected in the exams. One of the standout features of our estimate paper is that it can be downloaded for free, allowing you to print these important questions at no cost.

  • 9th Class Physics Chapter 5: Gravitation

    9th Class Chapter 5: Gravitation Short and Simple Question & Answer

    On this page, you will find the Physics Estimate Paper for Class 9 for the year 2024, available in both English and Urdu. We offer two formats for downloading the most important questions for Class 9 Physics. This estimate paper is suitable for all boards in Punjab, including BISE boards in Faisalabad, Lahore, Gujranwala, Dera Ghazi Khan, Sargodha, Sahiwal, Multan, and Jammu Kashmir. Many students have successfully used the Physics Estimate Paper 2024 by Faiz Ul Islam to achieve good results in their exams.

    Q1.Define gravitation.

    Ans: In the universe, there exists a force between the bodies due to which everybody of the universe attracts every other body. This force is known as force of gravitation.

    Q2.State law of gravitation.

    Ans: Every object in the universe attracts every other object with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

    Q3.What is the relation between Law of Gravitation and Newton’s Third law of motion?

    Ans: It is to be noted that mass m1 attracts m2 towards it with a force F while mass m2 attracts m1 with a force of the same magnitude F but in opposite direction. If the force acting on m1 is considered as action then the force acting on m2 will be reaction. The action and reaction due to force of gravitation are equal in magnitude but opposite in direction. This is in consistence with Newton’s third law of motion which states, to every action there is always an equal but opposite reaction.

    Q4.What is Gravitational Field Strength?  

    Ans: In the gravitational field of the Earth, the gravitational force per unit mass is called gravitational field strength of the Earth. At any place its value is equal to the value of g at that point. Near the surface of the Earth, the gravitational field strength is 10 Nkg-1.

    Q5.Define orbital velocity.

    Ans: It is the velocity of the satellite with which it moves around the earth at specific height.

    Q6.What do you know about Global Positioning System.

    Ans: Global Positioning System (GPS) is a satellite navigation system. It helps us to find the exact position of an object anywhere on the land, on the sea or in the air. GPS consists of 24 Earth satellites. These satellites revolve around the Earth twice a day with a speed of 3.87 km s-1.

    Q7.What will happen if Earth suddenly stops revolving around the Sun?

    Ans: If Earth suddenly stops revolving around the Sun then due to attraction of sun and earth, it will fall down on the sun.

    Q8.What do you know about geostationary satellites?

    Ans: Geostationary satellites are the satellites whose velocity relative to earth is zero. These satellites remain stationary with respect to the earth at the height of 42,300 km from the surface of the earth. These are used for global TV transmissions and other telecommunication purposes.

    Q9.What is effect of the followings on the gravitational acceleration?

    • Mass of freely falling body
    • Distance of freely falling body from the centre of earth

    Ans: Effect of mass

    There is no effect of mass of the body on gravitational acceleration because according to the relation g = GM/R2. This relation shows that gravitational acceleration is independent of the mass of freely falling body.

    Effect of distance from the center of earth

    Gravitational acceleration is inversely proportional to the square of distance of freely falling body from the centre of earth. If the distance of the body is increased from the centre of the earth gravitational acceleration will be less and vice versa.

    Q10.Is there any difference between the value of ‘g’ at the equator and at the poles?

    Ans: As the shape of the earth is not perfect sphere but elliptical. The distance at the equator to the center of earth is more, so gravitational acceleration ‘g’ at equator will be less. However, as the distance at the poles to the center of the earth is less, so gravitation acceleration ‘g’ will be more.

    Q11.Moon revolves around the earth, from where it gets necessary centripetal force?

    Ans: The gravitational force between the earth and the moon provides the necessary centripetal force to moon for revolving around the earth.

    Q12.If we go on top of the mountain, will our weight increase or decrease?

    Ans: If the distance from the centre of the Earth increases from the average radius of the Earth, the value of ‘g’ will decrease. This is the reason due to which the value of ‘g’ is less on the top of mountains. So our weight will be decreased.

    Q13.Why do not we observe force of attraction between any two objects around us?

    Ans: Since the gravitational force between different objects around us is very small, so we do not feel it. However, if the mass of one or both the objects is very large, then we can observe the effect of gravitational force easily.

    Q14.What is the gravitational force acting on the body placed at the surface of Earth?

    Ans: Since the mass of the Earth is very large, it attracts nearby objects with a significant force. The weight of an object on the Earth is a result of the gravitational attraction between the two.

    Download PDf Format

    When preparing for their final exams, students can utilize the 9th-grade Physics assessment paper. Every chapter from the textbook is covered, along with questions that may appear on the exam. These essential questions serve as valuable study aids after students have completed the entire syllabus. By focusing on these key concepts, students can gauge their understanding and boost their confidence, ultimately enhancing their exam performance.

    Class 9 Physics Estimate Paper 2024 for Punjab Board Students

    Physics is often considered a challenging subject. The exam date for Class 9 Physics papers has been released, with all Punjab Boards conducting these papers on Friday. With limited time for preparation, using these important questions can significantly aid in covering the essential topics.

    Additionally, these questions will enhance your knowledge and help you prepare for the crucial questions expected in the exams. One of the standout features of our estimate paper is that it can be downloaded for free, allowing you to print these important questions at no cost.

  • 9th Class Physics Chapter 4: Turning Effect of Forces

    9th Class Chapter 4: Turning Effect of Forces Short and Simple Question & Answer

    On this page, you will find the Physics Estimate Paper for Class 9 for the year 2024, available in both English and Urdu. We offer two formats for downloading the most important questions for Class 9 Physics. This estimate paper is suitable for all boards in Punjab, including BISE boards in Faisalabad, Lahore, Gujranwala, Dera Ghazi Khan, Sargodha, Sahiwal, Multan, and Jammu Kashmir. Many students have successfully used the Physics Estimate Paper 2024 by Faiz Ul Islam to achieve good results in their exams.

    Q. What is meant by parallel forces?
    Ans:     In a plane, if number of forces act on a body such that their points of action are different but lines of action are parallel to each other, then these forces are called parallel forces. In the given figure, the forces F1, F2, F3 are acting at points A, B, C are parallel forces.

    Q.What is meant by like parallel forces? Also give examples.
    Ans:
    Like parallel forces are the forces that are parallel to each other and have the same direction.
    Examples:
    In the second figure, the direction of the parallel forces F1 and F3 is the same, so these are like parallel forces.

    Q.What are unlike parallel forces?
    Ans:     Unlike parallel forces are the forces that are parallel but have direction opposite to each other.
    Example:
    In the second figure, the parallel forces F1, F2 and F2, F3 are acting in opposite direction, so these are unlike parallel forces.

    Q.Define head to tail rule.
    Ans: Draw the representative lines of all the vector to be added in such a way that head of first vector coincides with the tail of second vector, head of second vector coincides with the tail of third vector and so on. The line obtained by joining the tail of first vector with the head of last vector represent resultant vector.

    Resultant Force
    A resultant force is a single force that has the same effect as the combined effect of the all the forces to be added. And resultant vector is drawn in such a way that tail of first vector is joined with the head of the last vector.

    Q.Define resolution of vectors.
    Ans:     The decomposition or division of a vector into its rectangular components is called resolution of a vector.

    OR

    The splitting of a single force into two mutually perpendicular components is called the resolution of that force.

    Q.Define torque or moment of force.
    Ans:     The rotational effect of a force is measured by a quantity, known as torque.

    Q.Define centre of mass.
    Ans:     Centre of mass of a system is such a point where an applied force causes the system to move without rotation.

    Q.Define centre of gravity.
    Ans:     A point in a body where the weight of the body appears to act vertically downward is called the centre of gravity.

    The centre of gravity can exist inside a body or outside the body. Position of the centre of gravity depends upon the shape of the body.

    Q.Define couple and give examples.
    Ans:     A couple is formed by two unlike parallel forces of the same magnitude but not along the same line.

    Examples:
    While turning a car, the forces applied on the steering wheel by hands provide the necessary couple.
    While opening or closing a water tap,
    While locking or opening the stopper of a bottle or a jar.

    Q.Define equilibrium.
    Ans:     A body is said to be in equilibrium if no net force acts on it.

    State conditions of equilibrium.

    First Condition of equilibrium:
    A body will be in equilibrium if the resultant of all the forces acting on it is zero. This is first condition of equilibrium.

    Second Condition of equilibrium:
    If a number of forces act on a body so that the total sum of the torques of these forces is zero, the body will be in equilibrium.

    Q.Define stable equilibrium.
    Ans:     A body is said to in stable equilibrium if after a slight tilt it returns to its previous position.

    When body is in stable equilibrium, its centre of gravity is at the lowest position. When it is tilted, its centre of gravity rises. It returns to its stable state by lowering its centre of gravity. A body remains in stable equilibrium as long as the centre of gravity acts through the base of the body.

    Examples:
    Table, chair, box and brick lying on a floor.

    Q.Define unstable equilibrium.
    Ans:     If a body does not return to its previous position when sets after a slightest tilt is said to in unstable equilibrium.

    The centre of gravity of the body is at its highest point in the state of unstable equilibrium. As the body topples over about its base, its centre of gravity moves towards its lower position and does not return to its previous position.

    Examples:
    A stick standing vertically on the tip of a finger.
    A cone standing on the tip of a finger.

    Q.Define neutral equilibrium.
    Ans:     Neutral equilibrium

    If a body remains in its new position when disturbed from its previous position, it is said to be in a state of neutral equilibrium. In neutral equilibrium the centre of gravity of body remains at the same height, irrespective to its new position.

    Example:

    A ball lying on the horizontal surface
    Motion of wheel on plane surface.

    Q.Define rigid body and axis of rotation.
    Ans:     Rigid body
    A body is composed of large number of particles. If the distance between all these pairs of particles of the body do not change by applying a force then it is called a rigid body.

    Axis of rotation
    During rotation, the particles of the rigid body move in circles with their centres all lying on a line. This straight line is called the axis of rotation of the body.

    Q.What is meant by principle of moments?
    Ans:     A body is balanced, if the sum of clockwise moments acting on the body is equal to the sum of anticlockwise moments acting on it.

    A body initially at rest does not rotate if sum of all the clockwise moments acting on it is balanced by the sum of all the anticlockwise moments acting on it. This is known as the principle of moments.

    Examples:
    A pencil, a sphere, and cylinder, a roller, an egg lying horizontally on a flat surface.

    Q.How stability of a body is related with the Position of centre of mass?
    Ans:     To make the body stable, their centre of mass must be kept as low as possible. It is due to the reason, racing cars are made heavy at the bottom and their height is kept to be minimum.

    Q.what factors rotation produce in a body depend?
    Ans:     Rotation produced in a body depends on the following two factors:

    Magnitude of the force.
    The perpendicular distance between the line of action of the force and the axis of rotation, that is known as moment arm.

    Q.How can we increase torque by keeping the force constant?
    Ans:     We can increase the torque by increasing the perpendicular distance from the line of action of force to the point of rotation that is moment arm by keeping the force constant, according to the relation τ = rF

    Q.Can a moving body be in equilibrium? Explain.
    Ans:     Yes, if a body is moving with uniform velocity then the body is in equilibrium because neither linear nor rotational acceleration is produced in the body.

    Q.Will a body be in equilibrium under the action of a single force?
    Ans:     No,the body will not be in equilibrium because first condition of the equilibrium will not be fulfilled. Since single force can never be zero and linear acceleration will be produced. Therefore we can say that a body cannot be equilibrium under the action of a single force.

    Q.Can a body be in equilibrium if it is revolving clockwise under the action of a single force?
    Ans:     No, the body will not be in equilibrium because second condition of the equilibrium will not be fulfilled. Since single torque can never be zero and rotational acceleration will be produced. Therefore we can say that a body cannot be equilibrium under the action of a single torque.

    Q.Give an example of a case when the resultant force is zero but resultant torque is not zero.
    Ans:     In case of couple, two equal and opposite forces are acting on a same body but even then the body rotates. In this case resultant force is zero but resultant torque is not zero.

    Example:
    While turning a car, the forces applied on the steering wheel by hands produce rotation in the steering wheel.

    Q.How do we know whether a body is in a stable or unstable equilibrium due to position of its centre of gravity?
    Ans:     If after disturbance, the centre of gravity of the body is raised up as compared to the initial position then the body will be in the state of stable equilibrium and if after disturbance, the centre of gravity of the body is lowered down as compared to the initial position then the body will be in the state of unstable equilibrium.

    Download PDF Format

    When preparing for their final exams, students can utilize the 9th-grade Physics assessment paper. Every chapter from the textbook is covered, along with questions that may appear on the exam. These essential questions serve as valuable study aids after students have completed the entire syllabus. By focusing on these key concepts, students can gauge their understanding and boost their confidence, ultimately enhancing their exam performance.

    Class 9 Physics Estimate Paper 2024 for Punjab Board Students

    Physics is often considered a challenging subject. The exam date for Class 9 Physics papers has been released, with all Punjab Boards conducting these papers on Friday. With limited time for preparation, using these important questions can significantly aid in covering the essential topics.

    Additionally, these questions will enhance your knowledge and help you prepare for the crucial questions expected in the exams. One of the standout features of our estimate paper is that it can be downloaded for free, allowing you to print these important questions at no cost.

  • 9th Class Physics Chapter 3: Dynamics

    9th Class Chapter 3: Dynamics Short and Simple Question & Answer

    On this page, you will find the Physics Estimate Paper for Class 9 for the year 2024, available in both English and Urdu. We offer two formats for downloading the most important questions for Class 9 Physics. This estimate paper is suitable for all boards in Punjab, including BISE boards in Faisalabad, Lahore, Gujranwala, Dera Ghazi Khan, Sargodha, Sahiwal, Multan, and Jammu Kashmir. Many students have successfully used the Physics Estimate Paper 2024 by Faiz Ul Islam to achieve good results in their exams.

    Q.1 Define­ dynamics.
    Ans:     The branch of mechanics that deals with the study of motion of an object and the cause of its motion is called dynamics.

    Q.Define force.
    Ans:     A force moves or tends to move, stops or tends to stop the motion of a body. The force can also change the direction of motion of a body.
    Example:
    We can open the door either by pushing or pulling the door.
    A man pushes the cart. The push may move the cart or change the direction of its motion or may stop the moving cart.
    A batsman changes the direction of moving ball by pushing it with his bat.

    Q.Define inertia. Explain it with examples.
    Ans:     Inertia of a body is its property due to which it resists any change in its state of rest or of uniform motion.
    It depends on the mass of the body. Greater the mass of the body greater will be the inertia. Therefore, we can say that mass is the direct measure of inertia.
    Example 1:
    Take a glass cover it with a piece of cardboard. Place a coin on the cardboard. Nowkick the card horizontally with a jerk of your finger. The coin does not move with the cardboard with the inertia and falls in to the glass.
    Example 2:
    Cut a strip of paper. Place it on the table. Stack a few coins at its on end. Pull out thepaper strip under the coins with a jerk. We will succeed in pulling out the paper strip under the stacked coin without letting them to fall due to inertia.

    Q.What is momentum?
    Ans:     Momentum of a body is the quantity of motion it possesses due to its mass and velocity.
    The momentum ‘P’ of a body is given by the product of its mass m and velocity v. Thus
    P = m x v
    Quantity
    Momentum is a vector quantity.
    Unit
    SI unit of momentum is kg ms-1 or Ns.

    Q.5 State Newton’s First law of motion.
    Ans:     A body continues in its state of rest or of uniform motion in a straight line provided no net force acts on it.

    Q.6 Why Newton’s First law of motion is also called law of inertia?
    Ans:     According to Newton’s first law of motion “A body continues its state of rest or of uniform motion in a straight line provided no net force acts on it”.
    The property of a body due to which it resists any change in its state of rest or motion is known as inertia.
    On comparing the above two statements we find that statement of Newton’s first law of motion is in accordance with statement of inertia. Therefore Newton’s first law of motion is known as law of inertia.

    Q.7 State Newton’s Second law of motion.
    Ans:     When a net force ‘F’ acts upon a body, it produces an acceleration in the body direction of force and the magnitude of acceleration is directly proportional to the force and is inversely proportional to the mass of the body.
    Mathematically F = ma

    Q.8 What is the unit of force? Define it.
    Ans: Unit of Force
    In the System International, the unit of force is newton, which is represented by the symbol ‘N’.
    Newton
    “One newton is that force which produces an acceleration of 1 ms-2 in a body of mass 1 kg”.
    This unit of force can also be written as,
    1 N = 1 kg x 1 ms-2
    1 N = 1 kgms-2

    Q.9 State Newton’s Third law of motion
    Ans:     To every Action there is always an equal but opposite reaction.
    So 1kgms-1 = R.H.S = 1 N s

    Ans: Rate of change of momentum of a body is equal to the applied force on it and the direction of change in momentum is in the direction of the force.

    Q.19 Suppose you are running and want to stop at once. Surely you will have to produce negative acceleration in your speed. Can you tell from where does the necessary force come?

    Q.20 Define circular motion.

    Ans: Motion of the body moving in the circular path is known as circular motion. Heavenly bodies have natural tendency to move in curved paths.

    Examples:

    The motion of the moon around the Earth is nearly in circular orbit.
    The paths of electrons moving around the nucleus in an atom are also nearly circular.
    Motion of the stone tied with the string

    Q.Define centripetal force.
    Ans:     A force that keeps a body to move in a circle is known as centripetal force.

    Or
    A force which compels the body to move in the circular path is known as centripetal force.

    Q. Define centripetal acceleration
    Ans:     The acceleration produced by the centripetal force which is always directed towards the center of the circle is known as centripetal acceleration. It is represented by ac.

    Q. Define and explain centrifugal force. Is it a reaction of centripetal force?

    Ans: Definition
    The force which compels a body to move away from circular path is known as centrifugal force. This is reaction of centripetal force.

    Example:
    Consider a stone tied with a string moving in a circle. The necessary centripetal force acts on the stone through the string that keeps it in the move in a circle. According to Newton’s third law of motion, there exists a reaction to centripetal force. Centripetal reaction that pulls the string outward is sometimes the centrifugal force.

    Q.Why outer edge of the road is kept higher than inner edge (banking of road)? Explain.
    Ans:     When a car takes a turn, centripetal force is needed to keep it in its curved track. The friction between the tyres and road provides the necessary centripetal force. The car would skid away if the force of friction between the tyres and the road is not sufficient enough particularly when the roads are wet. Banking of a road means that the outer edge of a road is raised. Banking causes a component of vehicle’s weight to provide the necessary force while taking a turn. Thus banking of road prevents skidding of vehicle and thus makes the driving safe.

    Q.Explain the function of washing machine (dryer).
    Ans:     The dryer of a washing machine is basket spinner. They have perforated wall having large numbers of fine holes in the cylindrical rotor. The lid of the cylindrical container is closed after putting wet clothes in it. When it spins at high speed, the water from wet clothes is forced out through these holes due to lack of centripetal force.

    Q.Explain the function of cream separator.
    Ans:     Most modern plants use a separator to control the fat contents of various products. A separator is a high – speed spinner. It acts on the same principle of centrifuge machine. The bowl spins at very high speed causing the heavier contents of the milk to move outwards in the bowl pushing the lighter contents inwards towards the spinning axis. Cream or butterfat is lighter than other components in the milk. Therefore, skimmed milk, which is denser than cream is collected at outer wall of the bowl. The lighter part (cream) is pushed towards the center from where it is collected through a pipe.

    Q.Why a cyclist bend himself toward the inner side of the curved path while taking turn with high speed?
    Ans:     A cyclist bend himself toward the inner side of the curved path while taking turn with high speed to provide necessary centripetal force with his weight to take turn in circular path to avoid slipping.

    Q.Can a body move with uniform velocity in a circle? If not, why?
    Ans:     When a body is moving in circle it may have uniform speed but its velocity is non-uniform because direction of the body is changing at every instant.

    Q.Can a body move along a circle without the centripetal force?
    Ans:     When a body moves in a circular path, it does so under the action of centripetal force. This force is directed towards the center along the radius of the circle. As the radius is perpendicular to the tangent of the circle, the centripetal force keeps the body in circular path. Thus, in absence of centripetal force, the body cannot move in a circular path.

    Q.Moon revolves around the earth, from where it gets necessary centripetal force?
    Ans:     The gravitational force between the earth and the moon provides the necessary centripetal force to moon for revolving around the earth.

    Download PDF Format

    When preparing for their final exams, students can utilize the 9th-grade Physics assessment paper. Every chapter from the textbook is covered, along with questions that may appear on the exam. These essential questions serve as valuable study aids after students have completed the entire syllabus. By focusing on these key concepts, students can gauge their understanding and boost their confidence, ultimately enhancing their exam performance.

    Class 9 Physics Estimate Paper 2024 for Punjab Board Students

    Physics is often considered a challenging subject. The exam date for Class 9 Physics papers has been released, with all Punjab Boards conducting these papers on Friday. With limited time for preparation, using these important questions can significantly aid in covering the essential topics.

    Additionally, these questions will enhance your knowledge and help you prepare for the crucial questions expected in the exams. One of the standout features of our estimate paper is that it can be downloaded for free, allowing you to print these important questions at no cost.

  • 9th Class Physics Chapter 2: Kinematics

    9th Class Chapter 2: Kinematics Short and Simple Question & Answer

    On this page, you will find the Physics Estimate Paper for Class 9 for the year 2024, available in both English and Urdu. We offer two formats for downloading the most important questions for Class 9 Physics. This estimate paper is suitable for all boards in Punjab, including BISE boards in Faisalabad, Lahore, Gujranwala, Dera Ghazi Khan, Sargodha, Sahiwal, Multan, and Jammu Kashmir. Many students have successfully used the Physics Estimate Paper 2024 by Faiz Ul Islam to achieve good results in their exams. Many students have successfully used the Physics Estimate Paper 2024 by Faiz Ul Islam to achieve good results in their exams.

    Q.1 Define Kinematics
    Ans:     The study of motion of an object without discussing the cause of motion is called the kinematics.

    Q.2 Define dynamics.

    Ans: The branch of mechanics that deals with the study of motion of an object and the cause of its motion is called dynamics.

    Q.3 How you will define the rest?

    Ans: If a body does not change its position with respect to its surroundings then it is said to be in a state of rest.

    Surrounding are the places in its neighborhood where various objects are present.

    Q.4 How you will define the motion?

    Ans: If a body continuously changes its position with respect to its surroundings then it is said to be in a state of motion.

    Q.5 How we can say that rest and motion are relative states?

    Ans: The state of rest or motion of a body is relative. For example, a passenger sitting in a moving bus is at rest because he/she is not changing his/her position with respect to the other passengers sitting in the bus. But to an observer outside the bus, the passengers and objects inside the bus are in motion because they are changing their positions.

    Q.6 Define Rotatory motion.

    Ans: The spinning motion of a body around its axis is called rotatory motion.

    Example:

    • Motion of Earth around its geographical axis
    • Motion of wheel and steering wheel around its axis
    • Motion of a ceiling electric fan
    • Axis of Rotation
    • A line around which a body rotates is called axis of rotation.

    Q.Differentiate between circular motion and rotatory motion
    Ans:

    Circular motion Rotatory motion
    1. The motion of an object in a circular path is known as circular motion.
    2. In circular motion the point about which a body goes around is outside the body.

    3. Examples:

    · Motion of earth around the sun.

    · Motion of moon around the earth.

    1. The spinning motion of a body about its axis is called rotatory motion.
    2. In rotatory motion the line around which a body moves about is passing through the body itself.

    3. Examples:

    · Motion of earth about its geographical axis.

    · Motion of a wheel about its axis.

    Q.8 Define Vibratory motion.

    Ans: To and fro motion of a body about its mean position is known as vibratory motion.

    Examples:

    • Motion of swing back and forth about its mean position
    • Motion of pendulum of wall clock
    • Motion of see – saw
    • Motion of a body attached with a spring.

    Q.9 What do you know about scalar and vector quantities (LHR 2014, 2015)

    Ans: A physical quantity which can be completely described by its magnitude only is called a scalar. The magnitude of a quantity means its numerical value with an appropriate unit.

    Examples:

    Mass, length, time speed, volume, area, energy etc.

    Vector

    physical quantity which can be completely described by its magnitude along with its direction.

    Example:

    Velocity, force, displacement, momentum, torque etc.

    Q.10 How a vector is represented?

    Ans: Symbolical Representation

    A vector is represented symbolically by a letter (an alphabet) with an arrow drawn above or below the symbol as . A vector quantity can also be represented symbolically by using bold letters such as A.

    Graphical Representation

    Graphically, a vector can be represented by a line segment with an arrow head at its one end. The length of line, according to some selected scale, gives the magnitude of the vector and an arrow head at one end of the line gives the direction of the vector. The line AB drawn according to some selected scale with an arrow head represents the vector graphically.

    Q.11 What is Position?

    Ans: The term position describes the location of place or a point with respect to some reference point called origin.

    Example:
    Suppose you want to describe the position of your school from your home. Let the school be represented by S and home by H. The position of your school from your home will be represented by a straight line HS in the direction from H to S as shown in Fig.

    Q.12 What is meant by distance?

    Ans: Distance

    The total length/separation of a path between two points is known as distance between those points.

    Quantity

    It is a scalar quantity

    Unit

    Its SI unit is meter (m).

    Representation

    It is represented by “S”.

    Q.13 What do you know about Displacement?

    Ans: The shortest distance between two points is known as displacement which has magnitude and direction.

    Representation

    It is represented by “ ”.

    Quantity

    It is a vector quantity and it is directed from initial to final point.

    Unit

    Its SI unit is meter (m).

    Q.14 What do you know about speed?

    Ans: The distance covered by an object in unit time is known as its speed.

    Mathematical form

    If a body covers distance ‘S’ in time ‘t’ then its speed ‘v’ can be mathematically written as,

    Speed = Distance covered/Total time

    v = D × t

    Distance = speed x time

    S = v × t

    Quantity

    It is a scalar quantity.

    Unit

    SI unit of speed is meter per second (ms-1).

    Q.15 How you will define the uniform speed?

    Ans: If a body covers equal distances in equal intervals of time, however small the intervals may be, the speed of the body is said to be uniform.

    Q.16 Define variable speed.

    Ans: A body has variable speed if it covers unequal distances in equal intervals of time however short the interval may be.

    Q.17 A body is moving with uniform speed. Will its velocity be uniform?

    Ans: A body moving with uniform speed may have uniform or variable velocity.

    If the direction of the body is not changing then its velocity will also be uniform.

    Example 1

    A car moving with uniform speed in the straight line will have uniform velocity.

    If the direction of the body is changing then its velocity will be variable.

    Example 2

    A car moving with uniform speed in the circular path will have variable velocity because its direction changes at every point on the circle.

    Q.18 What do you know about velocity?

    Ans: The rate of displacement of a body is called velocity.

    Mathematical form

    Here is the displacement of the body moving with velocity in time t.

    Quantity

    It is a vector quantity and its direction is same as the direction of displacement.

    Unit

    SI unit of velocity is same as that of speed that is meter per second (ms-1).

    Q.19 What do you know about uniform velocity?

    Ans: A body has uniform velocity if it covers equal displacement in equal intervals of time however short the interval may be.

    Q.20 Define variable velocity.

    Ans: A body has variable velocity if it covers unequal displacement in equal intervals of timehowever short the interval may be.

    Q.21 Does speedometer of a car measure its velocity?

    Ans: The speedometer of a car measures only magnitude of velocity not the direction. Therefore, we can say that speedometer of the car does not measure its velocity. It measures only speed.

    Q.22 Why a body moving along a circle with uniform speed has variable velocity?

    Ans: A body moving along a circle with uniform speed has variable velocity because its direction is changing at every point on the circular path.

    Q.23 What is meant by the acceleration?

    Ans: The rate of change of velocity of a body is known as acceleration.

    Mathematical form

    If a body is moving with initial velocity ’vi’ and after some time ‘t’ its velocity becomes ‘vf’ then change in velocity will be vf–vi in time t.

    Unit

    SI unit of acceleration is meter per second per second (ms-2).

    Quantity

    It is a vector quantity.

    Q. What is meant by uniform acceleration?
    Ans:     If a body has equal changes in velocity in equal intervals of time, however small the intervals may be, then the acceleration of the body is said to be uniform.

    Q.25 Define variable acceleration.

    Ans: A body has variable acceleration if it has unequal changes in velocity in equal intervals of time however short the interval may be.

    Q.26 What is meant by positive acceleration and negative acceleration?

    Ans: Positive acceleration
    If the velocity of the body is increasing then acceleration will be positive. The direction of positive acceleration is the same in which the body is moving without change in its direction.

    Example:

    If a car is moving in straight line and the driver presses the accelerator the velocity of the car starts to increase. So the acceleration of the body will be positive.

    Negative acceleration or retardation
    If the velocity of the body is decreasing then acceleration will be negative. The direction of negative acceleration is opposite to the direction in which the body is moving. Negative acceleration is also called retardation or deceleration.

    Example:
    If the driver applies brake, the velocity will start to decrease. So acceleration of the body will be negative and direction of acceleration is opposite to the direction of velocity.

    Q. A body moving with uniform velocity. What will be its acceleration?

    Ans: A body is moving with uniform velocity then its acceleration will be zero because acceleration is defined as the rate of change of velocity. When the body is moving with uniform velocity, the change in velocity will be zero and therefore the acceleration will also be zero.

    Q. Can a body moving with certain velocity in the direction of east can have acceleration in the direction of west?
    Ans:     Yes, a body moving with certain velocity in the direction of east can have acceleration in the direction of west. It is the case when the velocity of the body decreases. When velocity decreases, acceleration is produced in opposite direction to the direction of motion.

    Q. What do you know about graph?
    Ans:     Graph is a pictorial way of presenting the information about the relation between various quantities. The quantities used in plotting a graph are called the variables.

    Q. Independent variable quantity

    Ans: The quantity which can be changed with our wish is called independent variable quantity.

    Q. Dependent variable quantity

    Ans: The quantity, value of which varies with the change in independent variable quantity is called the dependent variable quantity.

    Q. What do you know about gravitational acceleration?
    Ans:     If we neglect air resistance, then all the bodies either lighter or heavier will fall down with uniform acceleration. This uniform acceleration of freely falling bodies is known as gravitational acceleration. It is represented by ‘g’. Its value is 9.8ms-2, but for simplicity we shall use the value of g as 10ms-2. For bodies falling vertically downward ‘g’ is positive and for bodies moving vertically upward ‘g’ is negative.

    Q. How can we use equations of motion for bodies, which are falling freely under the gravity?
    Ans: Equations of motion can be used for bodies moving under gravity. In such cases we replace ‘a’ by ‘g’ and S by h. so equations of motion for bodies falling freely can be written as,

    vf = vi + gt

    h = vit + gt2

    2gh = vf2 – vi2

    Q. What are the points kept in mind when bodies are moving freely under gravity?
    Ans:     When bodies are moving in downward direction:

    Initial velocity ‘vi’ of the freely falling body will be zero
    Gravitational acceleration will be positive
    When bodies are moving in upward direction:

    Final velocity ‘vf’ of the body will be zero.
    Gravitational acceleration will be negative.

    Q. When a body is thrown vertically upward, its velocity at the highest point is zero. Why?
    Ans:     When a body is thrown vertically upward, it moves against the force of attraction of the earth. It slows down gradually and on reaching the highest point it comes to rest. That is why the velocity of a body becomes zero at the highest point.

    Download PDF Format

    When preparing for their final exams, students can utilize the 9th-grade Physics assessment paper. Every chapter from the textbook is covered, along with questions that may appear on the exam. These essential questions serve as valuable study aids after students have completed the entire syllabus. By focusing on these key concepts, students can gauge their understanding and boost their confidence, ultimately enhancing their exam performance.

    Class 9 Physics Estimate Paper 2024 for Punjab Board Students

    Physics is often considered a challenging subject. The exam date for Class 9 Physics papers has been released, with all Punjab Boards conducting these papers on Friday. With limited time for preparation, using these important questions can significantly aid in covering the essential topics.

    Additionally, these questions will enhance your knowledge and help you prepare for the crucial questions expected in the exams. One of the standout features of our estimate paper is that it can be downloaded for free, allowing you to print these important questions at no cost.

  • 9th Class Physics Chapter 1: Physical Quantities and Measurement

    9th Class Chapter 1: Physical Quantities and Measurement Short and Simple Question & Answer

    On this page, you will find the Physics Estimate Paper for Class 9 for the year 2024, available in both English and Urdu. We offer two formats for downloading the most important questions for Class 9 Physics. This estimate paper is suitable for all boards in Punjab, including BISE boards in Faisalabad, Lahore, Gujranwala, Dera Ghazi Khan, Sargodha, Sahiwal, Multan, and Jammu Kashmir. Many students have successfully used the Physics Estimate Paper 2024 by Faiz Ul Islam to achieve good results in their exams.

    Q.1 What is Science?
    Ans:     The knowledge gained through observations and experimentations is called science. The word science is derived from the Latin work scientia which mean knowledge.

    Q.2 What Physics?
    Ans:     Physics is that branch of science in which we study matter, energy and their interaction. The laws and principles of physics help us to understand nature.

    Q.3 What are the physical quantities?
    Ans:     All measurable quantities are called physical quantities. These are characteristics of every object which are used to be measured to specify them. These characteristics of the object are known as physical quantities.
    Example:
    Length, time, mass, force, speed, volume, volume, density etc.

    Q.4 What are the basic characteristics of physical quantities?
    Ans:     A physical quantity possesses at least two characteristics in common.
    (i) Numerical magnitude
    (ii) Unit in which it is measured.

    Q.5 What are the base quantities?
    Ans:     The physical quantities which form the foundation for other physical quantities are called base quantities. Base quantities are the quantities on the basis of which other quantities are expressed.
    Example: These are length, time, mass, electric current, intensity of light, quantity of matter, and temperature. These are seven quantities in total.

    Q.6 What are the derive quantities?
    Ans:     All the quantities, which can be described in terms of base quantities, are known as derived quantities. The quantities that are expressed in term of base quantities are called derived quantities.
    Example: Force, area, volume, density etc.

    Q.7 Why a standard unit is needed to measure a quantity correctly?
    Ans:     To measure a quantity, we need to compare it with some standard quantity. While measuring the physical quantity, we have to see that how many times this quantity is bigger or smaller than the standard quantity. Therefore stand unit is needed to measure a quantity correctly.

    Q.8 What do you know about International System of Units (SI)?
    Ans:     With the development in the field of science and technology, the need for commonly acceptable system of units was seriously felt all over the world particularly to exchange scientific and technical information. The eleventh General Conference on weight and Measures held in Paris in 1960 adopted a worldwide system of measurements called International system of units. The International system of units referred as SI.

    Q.9 What are the base units?

    Ans: The units that describe the base quantities are called base units. Each base quantity has its SI unit. There are seven base units. The following table shows the base quantities and its units.

    Q.10 What are derived units?

    Ans: The units used to measure derived quantities, which are derived from base units, are called derived units.

    • Example:
    • Unit of speed is meter per second (ms¹).
    • Unit of force is Newton (N).
    • Unit of volume is meter cube (m³)
    • Unit of charge is coulomb (C)

    Q.11 How numbers are expressed in Scientific Notation?
    Ans:     Very small or very large numbers are expressed conveniently by using the scientific method based as some power of ten multiplied by a number between 1 and 10.
    OR A simple but scientific way to write large or small numbers is to express in some power of
    ten.

    Q.12 What do you know about Meter Rule?
    Ans:     It is an instrument which is used in laboratories to measure the length of an object or distance between two points.
    Scale
    It is one meter long which is equal to 100 centimeters. Each centimeter is divided into 10 small divisions called millimeter (mm).
    Least count
    The least count of meter rule is 1mm. This is the minimum length that can be accurately measured by the meter rule.
    Precautions
    While measuring the length, or distance with the help of meter rule, we should kept the eye vertically above the reading point. The reading becomes doubtful if the eye is positioned either left or right to the reading point.

    Q.13 Explain the statement, “A micrometer screw gauge measures more accurately than a vernier calipers”.

    Ans: A micrometer screw gauge can measure more accurately than a vernier calliper because a micrometer screw gauge can accurately measure up to one hundredth part of a millimeter whereas vernier calipers can only measure accurately up to one tenth part of a millimeter.

    Q.14 What do you know about Lever balance?
    Ans:     A lever balance consists of a system of levers. When lever is lifted placing an object in one pan and standard masses on the other pan, the pointer of the lever system move. The pointer is brought to zero by varying standard masses.

    Q.15 What is electronic balance? What is its range? And how mass is measured by using electronic balance?
    Ans:     It is an instrument used to measure the mass of the body electronically.
    Range
    Electronic balance comes in various ranges; milligram ranges, gram ranges and kilogram ranges.
    Procedure to measure mass
    Before measuring the mass of the body, it is switched on, and its reading is set to zero.
    Next place the object to be weighted.
    The reading on the balance gives you the mass of the body placed over it.

    Q.16 What do you know about Measuring Tape?
    Ans:     Measuring tapes are used to measure length in meters and centimeters. Measuring tapes are used by blacksmith and carpenters.
    Formation:
    A measuring tape consists of a thin long strip of cotton, metal or plastic. It can measure generally 10 m, 20 m, 50 m, 100 m. Measuring tapes are marked in centimeters as well as in inches.

    Download PDF Format

    When preparing for their final exams, students can utilize the 9th-grade Physics assessment paper. Every chapter from the textbook is covered, along with questions that may appear on the exam. These essential questions serve as valuable study aids after students have completed the entire syllabus. By focusing on these key concepts, students can gauge their understanding and boost their confidence, ultimately enhancing their exam performance.

    Class 9 Physics Estimate Paper 2024 for Punjab Board Students

    Physics is often considered a challenging subject. The exam date for Class 9 Physics papers has been released, with all Punjab Boards conducting these papers on Friday. With limited time for preparation, using these important questions can significantly aid in covering the essential topics.

    Additionally, these questions will enhance your knowledge and help you prepare for the crucial questions expected in the exams. One of the standout features of our estimate paper is that it can be downloaded for free, allowing you to print these important questions at no cost.

  • 9th Class Chemistry Chapter 8: Chemical Reactivity

    9th Class Chapter 8: Chemical Reactivity Short and Simple Question & Answer

    We know you are looking for 9th class Chemistry Chapter 8 English medium notes according to the new syllabus for 2020. That’s why we have uploaded comprehensive, easy-to-understand, and precise notes for 9th class Chemistry tailored for the Punjab board session 2020-2021. You can download these notes or view them online. Many students practice 2024 Biology important questions by FAIZ UL ISLAM and get good marks in the exam.

    Q1: Define metal. How metals, can be categorized?

    Ans: Metals are the elements which are electropositive and form cations by losing electrons. Metals can be categorized in followings: a. Very reactive metals b. Moderately metals c. Least reactive metals

    Q2: Write down any two physical properties of metals.

    Ans: Physical properties of metals are: a. Almost all metals are solids. b. All metals have high melting and boiling points.

    Q3: Write down any two chemical properties of metals.

    Ans: Chemical properties of metals are: a. Metals can easily lose electrons and form positive ions b. Metals readily react with oxygen to form basic oxides.

    Q4: Define electropositive character.

    Ans: Metals have the tendency to lose their valence electrons. This property of a metal is called electropositive character or metallic character e.g. NaNa++ le

    Q5: Write down the trends of electropositive character in periodic table.

    Ans: Electropositive character increases down the group and decreases from left to right in a period.

    Q6: Why the 2nd ionization energy of magnesium is very high than the first one?

    Ans: The 2nd ionization energy of magnesium is very high because, it is difficult to remove second electron from the Mg ion as nuclear charge attracts the remaining electrons strongly. As a result of nuclear attraction size of the ion decreases. So, it is difficult to remove 2+ electron from magnesium ion.

    Q7: What type of elements are metals?

    Ans: The elements which are electropositive and form cation by losing electrons. This type of elements are metals.

    Q8: Name the metal which exists in liquid form.

    Ans: Mercury exists in liquid state at room temperature.

    Q9: What is the nature of metallic oxides?

    Ans: The metallic oxides are basic in nature because they change red litmus paper to blue.

    Q10: Which group of metals is highly reactive?

    Ans: Group-1 of the periodic table is highly reactive in nature.

    Q 11: Sodium metal is more reactive than magnesium. Why?

    Ans: Because sodium is oxidized easily and has low ionization energy whereas magnesium is not easily oxidized and has high ionization energy that is why sodium is more reactive.

    Q12: Name the metal which can be cut with knife?

    Ans: Sodium metal can be cut with knife.

    Q13: Name the best ductile and malleable metal.

    Ans: Cesium is the best ductile and malleable metal.

    Q14: Name the metal which is the poorest Conductor of heat?

    Ans: Lead metal is the poorest conductor of heat.

    Q15: What do you mean by malleable and ductile?

    Ans: Malleable means can be hammered into sheets and ductile means can be drawn into wires.

    Q16: What do you mean by metallic character?

    Ans: Metals have the tendency to lose their valence electrons. This property of metal is termed as metallic character.

    Q17: Why metallic character increases in group and decreases in a period?

    Ans: Metallic character increases in group and decreases in a period because top to bottom in a group atomic size increases and left to right in a period atomic size decrease.

    Q18: Define transition elements.

    Ans: The elements in which d-orbital’s are in the process of filling, constitute a group of metals called transition metals.

    Q19: Give the application of silver.

    Ans: Silver has important-applications in mirror industry.

    Q20: Why sliver is not used in pure form?

    Ans: Because, the formation of oxide or sulphide layer on the surface of silver, makes it relatively inactive in nature, therefore, silver is not used in pure form.

    Q21: What do you mean by 24 carat of Gold?

    Ans: Purity of gold is shown by carats. That indicates the number of parts by weight a gold that is present is 24 parts of alloy. 24 carrot gold is pure in nature.

    Q22: Why gold is used to make jewelry?

    Ans: Because of its inertness in atmosphere, it is an ornamental Metal so it is used to make jewelry.

    Q23: Why platinum is used for making jewelry?

    Ans: Platinum is used to make jewelry items because of its unique strength, flexibility and resistance to tarnish.

    Q24: Write down the difference between steel and stainless steel.

    Ans: Difference between steel and stainless steel is: Steel: Pure steels is the alloy of iron with other metals like nickel, tungsten Stainless steel: Stainless steel is the alloy of iron with chromium

    Q25: How platinum is used as a catalyst in automobile and what we advantage of this use?

    Ans: Platinum alloyed with palladium and rhodium is used as catalyst in automobiles as catalytic converter. They convert most of the gases being emitted by vehicles into less harmful carbon dioxide, nitrogen and water vapors.

    Q26: What are non-metals?

    Ans: Non-metals form negative ions (anions) by gaining electronegative in nature and form acidic oxides. electrons In this way non-metals are

    Q27: On what factor non-metallic character depends?

    Ans: The non-metallic character depends upon the electron affinity and electronegativity of the atom.

    Q28: Write down the non-metallic character r in periodic table.

    Ans: Non-metallic character decreases from top to bottom in any group and increases left to right in a period.

    Q29: Write down two physical properties of non-metals.

    Ans: Physical properties of non-metals are: a. Non-metals are non-conductor of heat and electricity. b. Non-metals have low melting and boiling points.

    Q30: Write down two chemical properties of non-metals.

    Ans: Chemical properties of non-metals are: a. Non-metals form ionic compounds with metals and covalent compounds by reacting with one another e.g. CO2, NO2 etc. b. Non-metals usually do not react with water.

    Q31: What are halogens?

    Ans: Halogen means salt former. Elements of group-7 of the periodic table consist of fluorine, chlorine, bromine iodine and astatine. They are collectively called halogens.

    Q32: Write down the physical properties of halogens.

    Ans: Both fluorine and chlorine exist in gases form, bromine exists in liquid form and iodine exists in solid form.

    Q33: Why valency of chlorine is 1?

    Ans: Valency of chorine atom is 1 because it accepts only | electron in its outermost shell.

    Q34: Which factor controls the non-metallic character of the elements?

    Ans: The non-metallic character depends upon the electron affinity and electronegativity of the atom.

    Q35: Why fluorine is more non-metallic than chlorine?

    Ans: Because non-metallic character decreases in a group downward and increases in a period from left to right. Fluorine is the first member of group 17 and non-metallic character decreases down the group that is why fluorine is more non-metallic than chlorine.

    Q36: Iodine exists in solid state; can it be beaten with hammer to form sheets?

    Ans: No, only solid substances or metals that have the ability to change in sheets by beaten with hammer.

    Q37: Can liquids and gases be brittle?

    Ans: No, because it is not the property of liquids and gases.

    Q38: Why the oxygen is called non-metal?

    Ans: Oxygen is non-metal because all non-metals form negative ions by negative ios gaining electrons.

    Q39: Name two non-metals which are both brittle and non-ductile.

    Ans: Silicon and graphite are two non-metals which are brittle and non-ductile.

    Q40: Name the most abundant non-metal in the earth crust.

    Ans: Oxygen has the highest percentage in earth s crust i.e. 47% and in ocean 86%

    Q41: Give the non-metallic trend of halogens.

    Ans: Non-metallic character decreases from top to bottom in halogens because of increasing atomic size of atoms.

    Q42: Why do the non-metals accept electrons readily?

    Ans: The non-metals accept electrons readily because non-metals are electronegative in Nature and electron deficient in nature so they form an anion by gaining electrons.

    Q43: Why non-metals do not react with dilute acid while metals do react with acid?

    Ans: The non-metals do not react with dilute acids because non-metals are itself electron acceptor and metals loss electrons readily.

    Q44: How we can distinguish a substance is metal or non-metals with the help of an acid?

    Ans: Yes, we can distinguish a substance is metal or non-metal with the help of an acid as: Metals: Metals react with dilute acids because metals are itself electron donors. Non-Metals: Non-metals do not react with dilute acids because non-metals are itself electron acceptors.

    Q45: Why is HF weak acid?

    Ans: Because HF does not release its proton easily due to presence of hydrogen bonding.

    Q46: Write down the names of very reactive metals.

    Ans: Potassium, sodium, calcium, magnesium and aluminum are the very reactive metals.

    Q47: Write down the names of moderately reactive metals.

    Ans: Zinc, Iron, Tin and Lead are the moderately reactive metals.

    Q48: Write down the names of least Reactive or Noble metals.

    Ans: Copper, mercury, silver and gold are the least reactive metals.

    Q49: Why reactivity of metals increase down the group?

    Ans: The reactivity of metals increases down the group because of increasing atomic size.

    Q50: State the physical properties of metals.

    Ans: The Physical properties of metals are as: a. Metals have high melting and boiling point b. Metals are good conductor of heat and electricity

    Q51: Why nitrogen forms compounds with alkaline earth metals directly?

    Ans: Because alkaline earth metals form stable nitride when heated with nitrogen directly.

    Q52: Why the second ionization energy of magnesium is higher than the first one?

    Ans: It becomes very difficult to remove second electron from the magnesium ion Mg+¹ because nuclear charge attracts the remaining electrons strongly as the result of this attraction size of the ion decreases.

    Q53: How oxygen reacts with group II metals?

    Ans:Alkaline earth metals are less reactive towards oxygen. They form oxides when heated with oxygen. 2Mg+O2→ 2MgO

    Q54: What is the relationship between electro positivity and ionization energy?

    Ans: Electro positivity depends upon the ionization energy which in turn depends upon size and nuclear charge of the atoms. So smaller sized atoms with high nuclear charge have high ionization energy. Atoms having high ionization energy are less electro positive or metallic.

    Q55: Why electro positivity decreases from left to right in a period?

    Ans: Because electropositive character depends upon the size of the atom. Electropositive character decreases across the period due to decrease in atomic size.

    Q56: How electro positivity depends upon the size and nuclear charge of an atom?

    Ans: Electropositive character depends upon the size of the atom, greater the size of the atom, greater will be the electropositive character and less nuclear charge. Smaller the size of the atom, smaller will be the electropositive character and greater nuclear charge

    Q57: Why ionization energies of alkaline earth metals are higher than alkali metals?

    Ans: Ionization energy of alkaline earth metals is high than alkali metals because the atomic size of alkaline earth metals are smaller and greater nuclear charge.

    Q58: Why silver and gold are less reactive?

    Ans: Silver and gold are less reactive because gold and silver are relatively inactive metals and they do re relatively not loss electron easily that’ t’s why gold and silver are less reactive.

    Q59: Can pure gold be used for making ornaments? If not why?

    Ans: No, pure gold cannot be used for making ornaments because gold is too soft and it always used in alloy form with copper, silver ror some other metals.

    Q60: Why copper is used for making electrical wire?

    Ans: Because it is good conductor of heat and electricity.

    Q61: What is the trend of variation of in densities of alkali metals?

    Ans: Densities of alkali metals increase down the group in the periodic table due to increase in atomic mass.

    Q62: Which metal is used for metal work?

    Ans: Metal work means fire work. The metals are used for the metal works or fire work due to its characteristics flame colour when they ignite in air for example sodium gives golden yellow colour and calcium gives red colour flame.

    Q63: Why magnesium is harder than sodium?

    Ans: Magnesium is harder than sodium because magnesium has high ionization energy and stronger metallic bond than sodium,

    Q64: Why calcium is more electropositive than magnesium?

    Ans: Calcium and magnesium are belonged to the same group and electro positivity of metals increases when we move from top to bottom in a group that is why calcium is more electropositive than magnesium.

    Q65: Why ionization energy of sodium is less than magnesium?

    Ans: Because sodium has greater size than magnesium that is why the ionization of sodium is less than magnesium.

    Q66: Why the ionization energy of sodium is more than potassium?

    Ans: Because electro positive character depends upon the ionization energy which in turn depends on size and nuclear charge of the atom. So the electro positive character increases down the group and ionization value decreases, it become easier to lose their electrons. That why ionization energy of sodium is more than potassium.

    Q67: Write down the uses of Sodium.

    Ans: Uses of Sodium are as: a. Sodium-potassium alloy is used as a coolant in nuclear reactor. b. It is used to produce yellow light in sodium vapour lamp. c. It is used as a reducing agent in the extraction of metals like Ti.

    Q68: Write down the uses of Calcium.

    Ans: Uses of Calcium as: a. It is used to remove Sulphur from petroleum products, b. It is used as reducing agent to produce Cr, U, Zr.

    Q69: Write down the uses of Magnesium.

    Ans: Uses of Magnesium are as: a. Magnesium is used in flash lights and in fireworks. in firew b. It is used in the manufacture of light alloys. c. Magnesium ribbon is used in Thermite process to ignite aluminum powder. d. Magnesium is used as anode for prevention of corrosion.

    Download PDF Format

    The 9th class Punjab Textbook of Chemistry is an excellent starting point for your scientific journey. Besides this book, it’s beneficial to gather additional information from various online resources. This post provides you with the 9th Class Notes for Chemistry, including multiple posts for each chapter. Each chapter post contains a variety of questions, including Short Questions, Long Questions, and Multiple-Choice Questions.

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    These 9th class notes are prepared according to the syllabus of all Punjab Boards, including Gujranwala Board, Lahore Board, Faisalabad Board, Multan Board, Rawalpindi Board, Bahawalpur Board, Sargodha Board, DG Khan Board, and Sahiwal Board.