Properties of Each State - UNSOLVED PRACTICE SET

Q7. Distinguish between crystalline and amorphous solids with one example of each.

Q8. What is surface tension? Give two examples from daily life that demonstrate this property of liquids.

Q9. Why do gases have low density compared to liquids and solids?

Q10. What is viscosity? Why does honey flow more slowly than water?

Q11. Why do solids generally expand on heating? Explain in terms of particle behaviour.

Q12. What is elasticity? Why do some solids return to their original shape after deformation while others do not?

Q13. Discuss the unique properties of solids, liquids, and gases. For each state, explain at least three properties and relate them to the arrangement and motion of particles.

Q14. Explain the following properties of liquids:

(a) Surface tension

(b) Viscosity

(c) Capillary action

How are these properties related to intermolecular forces?

Q15. Compare the properties of crystalline and amorphous solids. Discuss their structure, melting behaviour, and examples from daily life.

Q16. The coefficient of linear expansion of a metal rod is 12 × 10⁻⁶ /°C. A rod of this metal has a length of 2 m at 20°C.

(a) Calculate its length at 120°C.

(b) Calculate the change in length.

(c) If another metal has a coefficient of 24 × 10⁻⁶ /°C, which metal would be more suitable for making a measuring scale that must be accurate over a wide temperature range? Explain.

Q17. The surface tension of water at 20°C is 72.8 dyn/cm (or 0.0728 N/m).

(a) Calculate the force required to lift a thin wire frame of length 5 cm from a water surface.

(b) If the surface tension decreases to 58.9 dyn/cm at 100°C, calculate the percentage decrease and explain why hot water is less effective at supporting small insects.

(c) Explain why soap solution has lower surface tension than pure water and how this helps in cleaning.

Q18. In your school science fair, a student creates a project on properties of states of matter.

(a) She demonstrates that a steel needle can float on water due to surface tension. If the needle has a length of 4 cm and mass of 0.5 g, calculate the minimum surface tension required to support it (assume the needle is supported by surface tension along its length).

(b) She then shows that adding detergent to water makes the needle sink. Explain why detergent reduces surface tension and how this relates to the cleaning action of soaps.

(c) The student uses the example of a thermometer to explain thermal expansion. If a mercury thermometer has a bulb volume of 0.5 cm³ and capillary tube diameter of 0.2 mm, calculate how much the mercury column rises for a 10°C temperature increase. (Coefficient of volume expansion of mercury = 1.82 × 10⁻⁴ /°C)

(d) A classmate brings a rubber ball and a glass marble. He drops both from the same height. The rubber ball bounces back while the glass marble breaks. Explain this difference using the concepts of elasticity and plasticity.

(e) In the Indian context, traditional mud houses stay cool in summer and warm in winter. Explain how the properties of solids (mud bricks) and the presence of air pockets contribute to this thermal insulation.