Particulate Nature of Matter — Hard

Q1. Consider the following statements about the solid state: I. Particles in a solid are held in fixed positions by very strong interparticle attractions. II. The interparticle spacing in solids is the maximum among the three states. III. The particles in a solid can only vibrate about their positions. Which of the above are correct?

• A. I and II only
• B. II and III only
• C. I and III only
• D. All three

Q2. Assertion (A): On heating a solid to its melting point, it changes into a liquid. Reason (R): Heating increases particle vibrations until interparticle attractions are weakened and particles begin to leave their fixed positions.

• 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, R is false
• D. A is false, R is true

Q3. Three solids X, Y and Z have melting points 25 °C, 660 °C and 1538 °C respectively. Based on Table 7.1 reasoning, which solid is expected to have the strongest interparticle attractions?

• A. X, because its low melting point shows tightly packed strong bonds
• B. Z, because the highest melting point indicates the strongest interparticle attractions
• C. Y, because the middle value is always the most stable
• D. All three have equal attractions because they are all solids

Q4. When water in an open pan is heated beyond its boiling point, which sequence best describes what happens to its particles?

• A. Particles slow down, then attractions strengthen, and water becomes ice
• B. Particles vibrate without moving past each other and water stays liquid forever
• C. Particles spread evenly while volume keeps decreasing without any vapour forming
• D. Particle motion becomes very vigorous; interparticle attractions weaken so that particles escape into the gaseous state

Q5. A small amount of water spilled on the floor of a Rampur classroom disappears within an hour at room temperature, well below 100 °C. The best explanation is

• A. The water boils silently and turns into vapour without reaching the boiling point
• B. The floor chemically absorbs all the spilled water
• C. Evaporation occurs at all temperatures, only at the surface, even below the boiling point
• D. Water particles temporarily change into solid before vanishing

Q6. A teacher places a small amount of solid iodine in a closed gas jar. After some time, the jar is uniformly filled with violet vapour. This demonstrates that

• A. Iodine is heavier than air and sinks to the bottom only
• B. Solid iodine first becomes a liquid and then a gas
• C. Gases have no fixed shape or volume and occupy all available space
• D. Solid iodine reacts chemically with air to produce violet smoke

Q7. Consider the following statements: I. A gas can be compressed easily by applying pressure. II. A liquid is practically incompressible because its particles are already close together. III. A solid can be compressed more easily than a gas because its particles vibrate. Which of these are correct?

• A. I and II only
• B. II and III only
• C. I and III only
• D. All three

Q8. In Activity 7.7, the volume of the sugar solution at mark C is observed to be less than the sum of the volumes of plain water (at A) and dry sugar added. The best conclusion is

• A. Some water has evaporated during stirring
• B. Sugar has chemically reacted with water and lost mass
• C. There are spaces between water particles into which dissolved sugar particles fit
• D. The glass vessel has expanded due to stirring heat

Q9. Activity 7.7 is repeated with sand instead of sugar. Which observation is expected?

• A. Sand particles settle down and the total water level rises and stays raised
• B. Sand dissolves completely and the level falls below the original
• C. Sand evaporates and the water level falls below the original
• D. Sand reacts with water to form a sweet solution

Q10. The 'A step further' box on Suspended Particulate Matter (SPM) in air clarifies that

• A. SPM means the constituent particles (atoms and molecules) of air
• B. SPM is the layer of clean air above the polluted city
• C. SPM refers to tiny dust particles suspended in air, which themselves are made of very many constituent particles
• D. SPM is a non-particulate form of pollution

Q11. Assertion (A): Sand grains placed in water settle down at the bottom but do not spread throughout the water like potassium permanganate does. Reason (R): In sand, the constituent particles are held together so strongly that water particles cannot pull them out into the solution.

• 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, R is false
• D. A is false, R is true

Q12. Exercise 2 lists four statements. Which combination is correct as worded? I. Melting ice into water is an example of the transformation of a solid into a liquid. II. Melting process involves a decrease in interparticle attractions during the transformation. III. Solids have a fixed shape and a fixed volume.

• A. I and II only
• B. II and III only
• C. I and III only
• D. All three

Q13. Exercise 3 asks: if we could remove all the constituent particles from a chair, what would happen?

• A. Nothing will change because the chair will still be visible
• B. The chair will weigh less because some particles are lost
• C. Nothing of the chair will remain, because the chair is nothing but its particles
• D. Only the wooden parts of the chair will remain

Q14. Exercise 1: The primary difference between solids and liquids is that the constituent particles are

• A. Closely packed in solids, while they are stationary in liquids
• B. Far apart in solids and have fixed position in liquids
• C. Always moving in solids and have fixed position in liquids
• D. Closely packed in solids and move past each other in liquids

Q15. Exercise 5: Spilled milk from a glass tumbler flows and spreads on the table, but the tumbler keeps its shape. The best justification is

• A. Milk is denser than the glass tumbler, so it flows
• B. Glass is hotter than milk, so it stays in shape
• C. Milk particles are free to move past each other within a limited space (liquid), while glass particles are held in fixed positions by very strong attractions (solid)
• D. Milk is alive and so it moves, while glass is non-living and stays put