Class 6 Physics Revision Practice Questions
1. Multiple Choice Questions (30 × 1 = 30 marks)
* Which of the following is the SI unit of length?
a) Centimetre
b) Metre
c) Foot
d) Kilometre
Answer: b) Metre
* In which of the following, the intermolecular space is the largest?
a) Liquid
b) Solid
c) Gas
d) Vapour
Answer: c) Gas
* The push or pull on an object is known as:
a) Energy
b) Mass
c) Force
d) Temperature
Answer: c) Force
* Which of the following values is obtained when we convert 170 inches into centimetre? (1 inch = 2.54 cm)
a) 433
b) 434
c) 430
d) 431.8
Answer: d) 431.8
* The state of matter which has a definite volume but no definite shape is:
a) Solid
b) Liquid
c) Gas
d) Plasma
Answer: b) Liquid
* Which of the following is a non contact force?
a) Normal force
b) Tension
c) Muscular force
d) Magnetic force
Answer: d) Magnetic force
* The SI unit of mass is:
a) Gram
b) Milligram
c) Kilogram
d) Quintal
Answer: c) Kilogram
* Assertion: We use smaller units like millimeter when we measure the things which are small like the thickness of a wire.
Reason: Different units of lengths are used depending upon the need.
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true and R is not the correct explanation of A.
c) A is true, but R is false.
d) A is false, but R is true.
Answer: a) Both A and R are true and R is the correct explanation of A.
* The force of attraction between the molecules of the same substance is called:
a) Adhesive force
b) Cohesive force
c) Frictional force
d) Gravitational force
Answer: b) Cohesive force
* A leaf falling from a tree towards the ground is an example of:
a) Magnetic force
b) Electrostatic force
c) Gravitational force
d) Frictional force
Answer: c) Gravitational force
* Which of the following is the force produced by a machine?
a) Muscular force
b) Mechanical force
c) Frictional force
d) Tension
Answer: b) Mechanical force
* The device used to measure the mass of a body in a school laboratory is:
a) Spring balance
b) Beam balance
c) Measuring cylinder
d) Clinical thermometer
Answer: b) Beam balance
* The process of conversion of a liquid into its vapour state at any temperature below its boiling point is called:
a) Boiling
b) Condensation
c) Evaporation
d) Freezing
Answer: c) Evaporation
* A laboratory thermometer measures the temperature in the range of:
a) -20°C to 120°C
b) -10°C to 110°C
c) -5°C to 105°C
d) 35°C to 42°C
Answer: b) -10°C to 110°C
* The force that opposes relative motion between two surfaces in contact is:
a) Gravitational force
b) Frictional force
c) Magnetic force
d) Electrostatic force
Answer: b) Frictional force
* Which of the following are minimal particles that can exist independently and retain all their physical and chemical properties?
a) Elements
b) Molecules
c) Atoms
d) Compounds
Answer: b) Molecules
* Which instrument is used to measure the volume of an irregular solid?
a) Metre scale
b) Measuring cylinder
c) Beam balance
d) Stop clock
Answer: b) Measuring cylinder
* Assertion: When we spray perfume at one corner of the room, we can smell its fragrance in the entire room.
Reason: The molecules of air are in constant random motion.
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true and R is not the correct explanation of A.
c) A is true, but R is false.
d) A is false, but R is true.
Answer: a) Both A and R are true and R is the correct explanation of A.
* Which of the following states of matter is highly compressible?
a) Solid
b) Liquid
c) Gas
d) Both solid and liquid
Answer: c) Gas
* Which of the following is a non standard unit?
a) Metre
b) Cubit
c) Kilogram
d) Ampere
Answer: b) Cubit
* The SI unit of force is:
a) Dyne
b) Joule
c) Newton
d) Pascal
Answer: c) Newton
* 1 tonne is equal to:
a) 100 kg
b) 500 kg
c) 1000 kg
d) 10000 kg
Answer: c) 1000 kg
* 7 hectare equals to _______ m²:
a) 7000
b) 70000
c) 700000
d) 700
Answer: b) 70000
* Matter is defined as anything that:
a) Has mass and occupies space
b) Can only be felt
c) Has no mass but occupies space
d) Has mass but no volume
Answer: a) Has mass and occupies space
* The force exerted by a charged body on another charged or uncharged body is:
a) Gravitational force
b) Electrostatic force
c) Magnetic force
d) Muscular force
Answer: b) Electrostatic force
* The temperature of a normal human body is:
a) 98.6°C
b) 37°C
c) 100°C
d) 0°C
Answer: b) 37°C
* Solids have a fixed shape because:
a) Intermolecular force is very strong
b) Intermolecular space is very large
c) Molecules move freely
d) They have no mass
Answer: a) Intermolecular force is very strong
* The SI unit of time is:
a) Minute
b) Hour
c) Second
d) Day
Answer: c) Second
* Which of the following is an example of a contact force?
a) Gravitational force
b) Magnetic force
c) Frictional force
d) Electrostatic force
Answer: c) Frictional force
* The change of state from solid directly to gas without passing through liquid is called:
a) Melting
b) Sublimation
c) Freezing
d) Condensation
Answer: b) Sublimation
2. Name the Following (30 × 1 = 30 marks)
* A device used to measure the temperature.
Answer: Thermometer
* The standard unit of length in the SI system.
Answer: Metre
* The force exerted by a magnet.
Answer: Magnetic force
* The state of matter that has neither a fixed shape nor a fixed volume.
Answer: Gas
* The determination of a quantity which is unknown to us by using a similar quantity.
Answer: Measurement
* The force with which the Earth pulls all objects towards its centre.
Answer: Gravitational force (or Gravity)
* Type of a solid in which particles are not arranged in a fixed pattern.
Answer: Amorphous solid
* The instrument used to measure the time interval between the start and finish of an athletic event.
Answer: Stopwatch (or Stop clock)
* An attraction between molecules of matter that binds them together.
Answer: Intermolecular force of attraction
* The process of change of state from liquid to solid on cooling.
Answer: Freezing (or Solidification)
* The forces in which the two interacting bodies are in physical contact with each other.
Answer: Contact forces
* The unit of area equal to 100 square metres.
Answer: Are
* The friction that exists when the body is in contact are at rest with respect to each other.
Answer: Static friction
* The force exerted by the muscles of the body.
Answer: Muscular force
* The temperature at which a substance changes from its liquid state to its gaseous state on heating.
Answer: Boiling point
* The empty space between the molecules of a substance.
Answer: Intermolecular space
* The space occupied by a two dimensional figure on a plane.
Answer: Area
* The fixed standard quantity with which an unknown quantity is compared during measurement.
Answer: Unit
* The amount of matter contained in an object.
Answer: Mass
* The force exerted on a body when it is suspended by a stretched string.
Answer: Tension (or Tensile force)
* The temperature at which a pure solid melts into a liquid at normal atmospheric pressure.
Answer: Melting point
* A measuring vessel used in the laboratory to take a fixed volume of liquid (such as 25 mL or 50 mL).
Answer: Pipette (or Measuring flask)
* The friction between two surfaces when one body slides over the surface of another.
Answer: Sliding friction
* The force of attraction between the molecules of two different substances.
Answer: Adhesive force (or Adhesion)
* The SI unit of temperature.
Answer: Kelvin
* The change of a gas directly into a liquid on cooling.
Answer: Condensation (or Liquefaction)
* The force of friction developed when an object rolls over the surface of another object.
Answer: Rolling friction
* The space occupied by a three-dimensional object.
Answer: Volume
* The process of conversion of a solid directly into gas without turning into liquid.
Answer: Sublimation
* The force exerted by an electrically charged object on another charged or uncharged object.
Answer: Electrostatic force
True or False (25 × 1 = 25 marks)
* To measure the long lengths of a straight or curved objects measuring rulers are used.
Answer: False (A measuring tape is used to measure long lengths and curved objects; rulers are for short, straight lengths.)
* Mass is the measure of the quantity of matter contained in a body.
Answer: True
* Friction between the brake - shoe and the wheel slows down or stops the moving vehicle.
Answer: True
* Non-contact forces can act only when two bodies touch each other.
Answer: False
* Gases have a definite volume.
Answer: False (Gases have neither a definite shape nor a definite volume.)
* Intermolecular space is minimum in solids and maximum in gases.
Answer: True
* Liquids are almost incompressible like solids.
Answer: True
* The SI unit of area is square centimetre (cm²).
Answer: False (The SI unit of area is square metre, m².)
* A laboratory thermometer should always be kept upright and not tilted.
Answer: True
* Rolling friction is greater than sliding friction.
Answer: False (Rolling friction is much smaller than sliding friction.)
* 1 metre is equal to 1000 millimetres.
Answer: True
* Solids can diffuse into one another very rapidly.
Answer: False (Diffusion is negligible in solids because particles are tightly packed.)
* The pull of gravity acts on all objects on the surface of the Earth.
Answer: True
* While reading a measuring cylinder, the eye level should be aligned with the upper meniscus for water.
Answer: False (For water, the eye level must align with the lower meniscus.)
* Lubricants are used to increase friction between moving machine parts.
Answer: False (Lubricants like oil or grease are used to reduce friction.)
* The temperature of boiling water is 100°C at normal atmospheric pressure.
Answer: True
* Force cannot change the direction of motion of a moving body.
Answer: False (A force can change the direction of motion.)
* Molecules of matter are always in random motion.
Answer: True
* The parallax error occurs due to the incorrect positioning of the eye while taking readings on a scale.
Answer: True
* Muscular force is an example of a non-contact force.
Answer: False (It requires direct physical contact and is a contact force.)
* 1 hour is equal to 3600 seconds.
Answer: True
* During evaporation, cooling is produced.
Answer: True
* Electrostatic force can act from a distance without physical contact.
Answer: True
* A clinical thermometer has a kink or constriction in its capillary tube to prevent the mercury from falling back automatically.
Answer: True
* The intermolecular force of attraction is strongest in liquids.
Answer: False (It is strongest in solids.)
Definitions (15 × 2 = 30 marks)
* Freezing point
The constant temperature at which a liquid changes into its solid state on cooling at standard atmospheric pressure.
* Non-Contact Force
The force that acts on an object from a distance without any physical contact between the interacting bodies (e.g., gravitational force, magnetic force).
* Measurement
The process of comparing an unknown physical quantity with a known, fixed standard quantity of the same kind.
* Melting point
The constant temperature at which a solid changes into its liquid state on heating at standard atmospheric pressure.
* Intermolecular space
The empty space present between the constituent molecules or atoms of a given substance.
* Condensation
The process by which a substance in its gaseous or vapour state changes into its liquid state on cooling.
* Normal force
The contact force exerted by a surface on an object placed on it, acting perpendicular to the surface of contact.
* Frictional force (Friction)
The opposing contact force that comes into play whenever one surface moves, slides, or rolls over another surface, resisting relative motion.
* Mass
The total quantity of matter contained within a body, which remains constant regardless of location.
* Intermolecular force of attraction
The mutual force of attraction that exists between the molecules of a substance and holds them together.
* Sublimation
The physical process in which a solid directly turns into a gas or vapour on heating, without passing through the intermediate liquid state.
* Electrostatic force
The non-contact force of attraction or repulsion exerted by an electrically charged body on another charged or uncharged body.
* Area
The extent or measure of the surface occupied by a two-dimensional flat plane or boundary, expressed in square units.
* Contact Force
A force that acts on an object only when there is direct physical contact between the interacting bodies (e.g., muscular force, friction).
* Boiling point
The fixed temperature at which a liquid rapidly turns into its gaseous state throughout the volume of the liquid at standard atmospheric pressure.
1. Two identical balloons were filled with air: one was kept in the fridge and the other kept in sunlight. After some time, the balloon in sunlight expanded, while the one in the fridge shrank. Why?
Answer:
When the balloon is kept in sunlight, the air molecules inside absorb heat energy. Their kinetic energy increases, causing them to move faster and spread farther apart, which increases the volume and causes the balloon to expand. In contrast, inside the fridge, the air molecules lose heat energy, their kinetic energy decreases, and they come closer together, leading to contraction (shrinkage) of the balloon.
2. Write the formula to find the area of the following plane figures:
a) Rectangle
b) Triangle
c) Circle
Answer: refer book
3. If a person jumps off a boat and the boat moves backwards, what force is at play here? During tug of war, both teams pull the rope with equal force but the rope doesn't move. Analyse and explain why the rope stays in the same position.
Answer:
* When a person jumps off a boat, an action-reaction force pair is at play. The person exerts a backward pushing force (action) on the boat, and the boat exerts an equal and opposite forward force (reaction) on the person, causing the boat to move backward.
* In a tug of war, when both teams pull with equal magnitude in opposite directions, the forces are balanced forces. The net resultant force on the rope is zero, so the rope remains stationary.
4. What is meant by mass, and what is its standard SI unit?
Answer:
Mass is the quantity of matter contained in a body. Its SI unit is the kilogram (\text{kg}).
5. A truck and a car are moving at the same speed. Which one will need more force to stop and why?
Answer:
The truck will require more force to stop. A truck has a much larger mass than a car.
6. What are the factors that affect friction between two surfaces?
Answer:
* The nature of the surfaces in contact (roughness or smoothness).
* The normal force pressing the two surfaces together (weight of the object).
(Note: Friction is independent of the apparent area of contact).
7. Write any two methods each to increase and decrease friction.
Answer:
* Methods to increase friction:
* Making the surfaces rough (e.g., grooves in automobile tyres or spikes on athlete shoes).
* Applying sand or gravel on slippery, snow-covered roads.
* Methods to decrease friction:
* Polishing the surfaces to make them smooth.
* Using lubricants like oil, grease, or graphite between moving parts.
8. Define volume. State its SI unit and its relationship with the litre.
Answer:
Volume is the three-dimensional space occupied by an object. Its SI unit is the cubic metre. 1m³ = 1000 litres
9. Write the numerical value (as powers of 10) of the following prefixes:
a) peta
b) mega
Answer:
a) peta = 10¹⁵
b) mega = 10⁶
10. Write any three characteristic properties of molecules of matter.
Answer:
* Molecules are extremely small in size.
* Molecules have empty spaces between them, called intermolecular spaces.
* Molecules are in a state of continuous random motion and possess kinetic energy.
(Also: Molecules exert attractive forces on one another, called intermolecular forces).
11. Why do we use mercury as a thermometric fluid? Mention four reasons.
Answer:
* It is a good conductor of heat.
* It does not stick to the glass walls of the thermometer tube.
* It has a uniform and regular rate of expansion over a wide range of temperatures.
* It is an opaque, shiny silvery-white liquid, making the meniscus easily visible.
12. How does the kinetic theory explain why solids have a fixed shape and a fixed volume?
Answer:
In solids, the constituent molecules are closely packed with negligible intermolecular spaces. The intermolecular forces of attraction are very strong, holding the molecules in fixed positions.
13. Noel steps out of an air-conditioned car on a humid day and his glasses become foggy. What caused this to happen?
Answer:
The lenses of Noel's glasses were chilled inside the cold air-conditioned car. When he stepped outside into the warm, humid air, the water vapour in the surrounding atmosphere came in contact with the cold surface of his glasses, lost heat, and condensed into tiny droplets of liquid water, forming fog on the glass.
15. Differentiate between a clinical thermometer and a laboratory thermometer (any two points).
Answer:
* Range: A clinical thermometer has a short range of whereas a laboratory thermometer has a wide range,
* Constriction (Kink): A clinical thermometer has a narrow kink in its capillary tube to prevent the backflow of mercury so the reading can be taken after removal, whereas a laboratory thermometer has no kink and must be read while immersed in the substance.
16. What is parallax error, and how can it be avoided while taking readings with a ruler?
Answer:
Parallax error is an apparent shift in the position of an object or mark caused by an improper angle of viewing. It can be avoided by placing the eye vertically above and exactly in line with the mark being read.
17. Give reasons for the following:
a) SI units are preferred over other unit systems.
b) Tyres of vehicles have deep grooves.
c) If we burn an incense stick in one corner of a room, its fragrance spreads across the entire room.
Answer:
a) SI units are internationally accepted standard units based on the metric system, ensuring uniform, reproducible, and error-free scientific and commercial communication worldwide.
b) Grooves provide a rough tread pattern that increases friction between the tyres and the road surface, preventing skidding and ensuring better grip, especially on wet roads.
c) Molecules of the scented smoke possess high kinetic energy and diffuse rapidly into the spaces between the constantly moving air molecules, spreading throughout the room.
18. Answer the following questions regarding sublimation:
a) What do you observe when camphor or dry ice is left in an open dish at room temperature?
b) What is the name of the process in which a solid directly changes into a gas without passing through the liquid state?
c) How is this process different from melting and boiling?
Answer:
a) The solid camphor or dry ice gradually decreases in size and disappears without leaving behind any liquid residue.
b) Sublimation.
c) Melting involves a change of state from solid to liquid, and boiling involves a change from liquid to gas; sublimation bypasses the liquid phase entirely, going directly from solid to gas.
19. Write any four general properties of solids.
Answer:
* Solids have a fixed shape and a definite volume.
* Solids are rigid and cannot be compressed easily.
* Solids have high densities compared to liquids and gases.
* Solids do not diffuse or flow.
20. State the two effects that a force can produce on a body.
Answer:
* A force can change the state of rest or of uniform motion of a body (its speed or direction).
* A force can change the shape and size (dimensions) of a body.
21. List the safety measures/precautions to be taken while measuring temperature with a laboratory thermometer.
Answer:
* The thermometer should be kept strictly upright, not tilted.
* The bulb should be completely surrounded by the substance whose temperature is being measured and must not touch the bottom or sides of the container.
* The reading must be recorded while the bulb is still in contact with the substance.
* The line of sight of the eye must be kept level with the top of the mercury meniscus.
22. A person is pushing a cart with a force of 20 N. Another person pushes the same cart from the opposite direction with a force of 15 N. What is the net force acting on the cart?
Answer:
* Net force = 20N -- 15 N = 5N
23. Write any four differences between the properties of gases and liquids.
Answer:
* Shape: Liquids have a definite volume but take the shape of the container; gases have neither a definite shape nor a definite volume.
* Intermolecular space: Intermolecular space in liquids is moderate; in gases, it is very large.
* Intermolecular force: Intermolecular force is fairly strong in liquids; in gases, it is negligible.
* Compressibility: Liquids are almost incompressible; gases are highly compressible.
24. What is meant by a non-contact force? Give two examples.
Answer:
A non-contact force is a force that acts on an object from a distance without physical contact between the interacting bodies.
Examples: Gravitational force, Magnetic force (or Electrostatic force).
25. How is the volume of a small, irregular stone measured using a measuring cylinder? Explain briefly.
Answer: please follow answer given in class point wise
26. Why does friction produce heat? Give an everyday example.
Answer:
When two surfaces move past each other, mechanical energy is expended to overcome the interlocking of surface irregularities. This mechanical work is converted into heat energy.
Example: Rubbing our palms together in winter makes them feel warm.
27. Define Brownian motion. What does it prove about the nature of matter?
Answer:
Brownian motion is the continuous, rapid, zig-zag (random) motion of microscopic suspended particles in a fluid. It proves that:
* Matter is made up of tiny particles (molecules).
* The molecules of matter are in constant random motion.
28. What is the difference between cohesive force and adhesive force?
Answer:
* Cohesive force: The attractive force acting between molecules of the same substance (e.g., attraction between water molecules).
* Adhesive force: The attractive force acting between molecules of different substances (e.g., attraction between water molecules and glass).
29. Why are handles of doors placed near the free edge and away from the hinges?
Answer:
The turning effect of a force depends both on the perpendicular distance from the axis of rotation (hinges).
30. Name two natural periodic events used by ancient people to measure time before the invention of clocks.
Answer:
* The periodic rising and setting of the Sun (a solar day).
* The regular changing phases of the Moon (a lunar month).
31. Explain why water forms spherical droplets on a waxy leaf surface.
Answer:
On a waxy leaf, the cohesive forces between water molecules are much stronger than the adhesive forces between water and wax. The water molecules pull tightly inward toward each other, causing the water to minimize its surface area and form spherical droplets rather than spreading out.
32. What is rolling friction, and why are wheels and ball bearings used in machinery?
Answer:
Rolling friction is the opposing force encountered when an object rolls over a surface. Wheels and ball bearings are used because rolling friction is significantly smaller than sliding friction, which drastically reduces energy loss and wear and tear in moving parts.
33. Define boiling point. State the boiling point of pure water at standard atmospheric pressure.
Answer:
The boiling point is the constant temperature at which a liquid rapidly changes into its gaseous state throughout the volume of the liquid at standard atmospheric pressure. The boiling point of pure water is 100°C
34. State whether the following statements represent contact or non-contact forces:
a) A batsman hitting a cricket ball with a bat.
b) An apple falling from a tree to the ground.
c) Iron pins pulled towards a bar magnet.
d) A horse pulling a cart.
Answer:
a) Contact force
b) Non-contact force (Gravitational force)
c) Non-contact force (Magnetic force)
d) Contact force (Muscular/Tension force)
35. A rectangular metal plate has a length of 12cm and a breadth of 8cm. Calculate its area in square centimetres and in square metres.
Answer:
* * Area = (12 x 8 ) cm² = 96 cm²
In m² = 0.0096 m²
36. Why is a person able to walk on the ground without slipping? What happens when a person steps on a banana peel?
Answer:
When walking, our foot pushes backward against the ground, and the force of friction between the sole of the footwear and the ground provides the necessary forward reaction force to prevent slipping. When stepping on a banana peel, the smooth, slimy surface drastically reduces friction, causing the foot to slip forward and making the person fall.
37. How does the arrangement and motion of molecules change when a liquid is heated to become a gas?
Answer:
When heated, the liquid molecules gain kinetic energy and vibrate more vigorously. As temperature rises to the boiling point, the molecules overcome the intermolecular forces holding them together, move far apart from one another, and begin moving freely in all directions, transitioning into the gaseous state.
38. What is a leap year? How many days does it have?
Answer:
A leap year has 366 days instead of 365 days.
39. Differentiate between mass and weight (any two points).
Answer:
* Definition: Mass is the amount of matter in an object, whereas weight is the gravitational pull exerted by the Earth on that object.
* Constancy: Mass remains constant everywhere in the universe, while weight changes depending on the acceleration due to gravity (g) of the location.
(Also: Mass is measured in kilograms using a beam balance; weight is measured in newtons using a spring balance).
40. Why do gases fill completely any container in which they are placed?
Answer:
In gases, the intermolecular forces of attraction are almost negligible and the molecules have high kinetic energy. As a result, they move freely and continuously at high speeds in all available directions until they fill the entire volume of the container.
Comments
Post a Comment
This site is all about helping you kids study smart because for Gen Z, studying "hard" is not enough. If you feel there is any way I could improve my posts or if you have any random suggestion that might help make this more kid friendly, please don't hesitate to drop in a comment!
Be sure to check back for my response if you've asked me a question or requested a clarification through the comment section because I do make every effort to reply to your comments here.