Question Bank — Particulate Nature of Matter

Section A — MCQs (1 mark each)

1. Which of the following correctly describes the arrangement of constituent particles in a solid?
   (a) Particles are far apart and move freely
   (b) Particles are closely packed with strong interparticle attractions and can only vibrate
   (c) Particles have large interparticle spaces and negligible attractions
   (d) Particles move past each other within a fixed volume

2. When sugar is dissolved in water, the volume of the resulting solution is observed to be slightly less than the sum of the volumes of water and sugar. This occurs because:
   (a) Sugar particles occupy the interparticle spaces in water
   (b) Water particles expand on adding sugar
   (c) Sugar melts and mixes completely
   (d) Interparticle attractions in water increase

3. Assertion (A): Liquids have a definite volume but no fixed shape.
   Reason (R): In liquids, interparticle attractions are weaker than in solids, allowing particles to move within a limited space while remaining close together.
   (a) Both A and R are true and R is the correct explanation of A
   (b) Both A and R are true but R is not the correct explanation of A
   (c) A is true but R is false
   (d) A is false but R is true

4. The fragrance of an incense stick lit in one corner of a room spreads throughout the room because:
   (a) Particles of air are stationary
   (b) Gas particles move freely in all directions and collide with fragrance particles
   (c) Fragrance particles are heavier than air
   (d) Interparticle spaces in solids allow fragrance to pass

5. Assertion (A): Gases can be easily compressed while liquids are almost incompressible.
   Reason (R): Interparticle spacing is maximum in gases and minimum in liquids.
   (a) Both A and R are true and R is the correct explanation of A
   (b) Both A and R are true but R is not the correct explanation of A
   (c) A is true but R is false
   (d) A is false but R is true

6. Which activity demonstrates that particles in liquids are in constant motion?
   (a) Hammering an iron nail
   (b) Placing potassium permanganate grains in water and observing the spread of pink colour
   (c) Pushing the plunger of a syringe filled with water
   (d) Breaking a chalk stick into pieces

7. The temperature at which a solid changes into a liquid at atmospheric pressure is called its:
   (a) Boiling point
   (b) Melting point
   (c) Freezing point
   (d) Evaporation point

8. In which state of matter do constituent particles have negligible interparticle attractions and occupy the entire available space?
   (a) Solid
   (b) Liquid
   (c) Gas
   (d) Both liquid and gas

9. When water is transferred from one container to another of different shape, the level remains the same but the shape changes. This shows that liquids:
   (a) Have fixed shape and fixed volume
   (b) Have no fixed shape but fixed volume
   (c) Have fixed shape but no fixed volume
   (d) Have neither fixed shape nor fixed volume

10. The process by which vapour forms slowly at the surface of a liquid at any temperature below its boiling point is called:
    (a) Boiling
    (b) Melting
    (c) Evaporation
    (d) Condensation

Section B — Very Short Answer (2 marks each)

1. What are constituent particles of matter? Give one example from the chapter.

2. Why can we move our finger through water but not through a solid piece of wood?

3. State two differences between interparticle attractions in solids and gases.

4. What happens to the movement of particles when a solid is heated to its melting point?

5. Why does the level of water decrease slightly after sugar dissolves completely in it?

6. Name the ancient Indian philosopher who proposed the idea of Parmanu and mention the name of his work.

Section C — Short Answer (3 marks each)

1. Explain, with the help of an activity described in the chapter, why gases do not have a fixed volume.

2. Differentiate between boiling and evaporation on the basis of temperature, location of vapour formation, and speed of the process.

3. Why do solids have a definite shape while liquids take the shape of the container? Relate your answer to interparticle spacing and attractions.

4. Describe what is observed when potassium permanganate grains are placed in water at different temperatures (hot, room temperature, and ice-cold). What does this indicate about particle movement?

5. How does the arrangement of particles change when ice melts into water? Mention the role of interparticle forces.

Section D — Long Answer (5 marks each)

1. Draw a labelled schematic diagram showing the arrangement of particles in solid, liquid, and gaseous states. Explain the differences in interparticle spacing, strength of attractions, and movement of particles in each state.

2. Describe Activity 7.7 (dissolving sugar in water) in detail. What does the change in water level after dissolution indicate about interparticle spaces in liquids? How is this different from adding sand to water?

3. Explain, step by step, how heating affects the state of matter using the example of ice converting to water and then to vapour. Include the role of thermal energy and interparticle attractions in your answer.

Section E — Case/Source-Based (4 marks each)

Case 1:

A student performs an activity by lighting an incense stick in one corner of a closed room. After a few minutes, the fragrance is noticed in all parts of the room even though the stick is not moved.

(i) What does this observation indicate about the movement of gas particles?
(ii) How do air particles help in spreading the fragrance?
(iii) Name another activity from the chapter that also demonstrates movement of particles in gases.
(iv) Why is this property useful in daily life? Give one example.

Case 2:

In an experiment, a glass vessel is half-filled with water and marked at level A. Two teaspoons of sugar are added and the new level is marked B. After stirring until the sugar dissolves completely, the level is marked C.

(i) What change is observed between levels A and B?
(ii) What happens to the level after complete dissolution (compare B and C)?
(iii) What does the final observation tell us about interparticle spaces in water?
(iv) Predict what would happen if sand were used instead of sugar. Give reason.

Section F — HOTS and Application (3 marks each)

1. Predict-and-justify: What would happen to the fragrance spreading activity if the room is made completely airtight and extremely cold? Justify using the concept of particle movement.

2. Analyse an anomalous observation: In an experiment, students observe that the pink colour of potassium permanganate spreads fastest in hot water but very slowly in ice-cold water. Explain this observation with reasoning about particle behaviour at different temperatures.

3. Apply to unfamiliar situation: A bottle of perfume is opened in a corner of a large hall during winter. People sitting far away can still smell it after some time. Apply the particulate nature of matter to explain how this happens, even though perfume particles are not visible.

4. Compare two situations: Situation X: A piece of iron is hammered. Situation Y: Water is stirred with a finger. In which situation do the particles return to their original positions more easily after the disturbance is removed? Justify using interparticle attractions and movement.