5. In which of the following, the particles have highest forces of attraction?
Water, NaCl (solid), water, oxygen
6. Which of the following diffuses faster?
Water vapour, wax or, ethyl alcohol.
7. Can a rubber band change its shape on stretching? Is it a solid?
8. Substance ‘A’ has high compressibility and can be easily liquefied. It can take up the shape of any
container. Predict the nature of the substance. List out four properties of this state of matter.
9. Describe the continuous motion of particles of matter with the help of an activity.
10. Why steam at 100°C is better for heating purposes than water at 100°C?
11. Why does the temperature of a substance remain constant during its melting point or boiling point?
12. What do you understand by the term ‘latent heat of fusion’? How much is the latent heat of fusion of
ice?
13. Describe an activity to determine the boiling point of water and melting point of ice.
14. While heating ice in a beaker with a thermometer suspended in it, a student recorded the following
observations:
Based on the above observations, answer the following questions:
(a) State the change(s) observed between 2-3 min. Name the process involved in it.
(b) Between 30-35 min., the temperature remains constant. State the reason for this. Name the heat
Answers
Answer:
Q7 rubber band is considered a solid because it changes shape under the action of force and when the force is removed, it regains its original shape.
Q10 Steam at 100°C has more heat than water at the same temperature. Water gets converted into steam on gaining heat. Due to this latent heat of vaporisation, steam at 100°C is better for heating than boiling water at 100°C
q11 The extra heat supplied to the boiling water is used in the vaporization of a liquid, which is known as the latent heat of vaporization. That's why the temperature of a substance remains constant during its melting or boiling
q12 The amount of heat that is required to change 1 kg of solid into liquid at atmospheric pressure without any change in temperature at its melting point, is known as latent heat of fusion. The latent heat of fusion of ice in SI unit is 3.35 x 10^5 J/kg