Questions in Short/Long Answer Questions

Q1) What is matter? What is it composed of.

Q2) Name the three states of matter and distinguish them on the basis of their (i) volume, and (ii) shape

Q3) Distinguish between liquid and vapour (or gas) states of matter on the basis of following factors

(a) Arrangement of molecules

(b) Intermolecular separation

(c) Intermolecular force, and

(d) Kinetic energy of molecules

Q4) What is evaporation? Explain it on the basis of molecular motion.

Q5) Do all molecules of a liquid take part in evaporation? If not, explain your answer.

Q6) No heat is supplied to a liquid during evaporation. How does then the liquid change into its vapours?

Q7) Comment on the statement, ‘evaporation is a surface phenomenon’.

Q8) Why is cooling produced when a liquid evaporates?

Q9) Give reasons for the increase in rate of evaporation of a liquid

(a) When air is blown above the liquid.

(b) When surface area of liquid is increased

(c) When temperature of liquid is increased.

Q10) What is boiling? Explain it on the basis of molecular motion?

Q11) Why does bubbles appear when a liquid is heated?

Q12) What is the change in average kinetic energy of molecules of a liquid during boiling at its boiling point?

Q13) How is the heat energy supplied to a liquid used during boiling at a fixed temperature?

Q14) Name two ways of change of liquid state to the vapour state and distinguish them.

Q15) What do you understand by thermal expansion of a substance?

Q16) Give two examples of the substance which expand on heating.

Q17) Describe an experiment to demonstrate the thermal expansion in solids.

Q18) State three factors on which depend the linear expansion of a metal rod on heating.

Q19) Two iron rods - one 10 m long and other 5 m long, are heated to the same rise in temperature. Which will expand more?

Q20) Two identical rods of copper are heated to different temperatures - one by 5°C and the other by 10°C. Which rod will expand more?

Q21) One rod of copper and another identical rod of iron are heated to the same rise in temperature. Which rod will expand more? Give reason.

Q22) Two identical rods - one hollow and the other solid, are heated to the same rise in temperature. Which will expand more?

Q23) In the ball and ring experiment, if the ball after heating is left to cool on the ring for sometime, the ball again passes through the ring. Explain the reason.

Q24) Explain the following:

(a) The telephone wires break in winter.

(b) Iron rims are heated before they are fixed on the wooden wheels.

(c) The gaps are left between the successive rails on a railway track.

(d) A glass stopper stuck in the neck of a bottle be removed by pouring hot water on the neck of the bottle.

(e) A cement floor is laid in small pieces with gaps in between.

Q25) Why is one end of a steel girder in a bridge kept on rollers instead of fixing it in pillar?

Q26) A metal plate is heated. State three factors on which increase in its area will depend.

Q27) A cubical metal solid block is heated. How will its volume change?

Q28) Describe an experiment to show that liquids expand on heating.

Q29) State one application of thermal expansion of liquids.

Q30) Describe an experiment to show that air expands on heating.

Q31) An empty glass bottle is fitted with a narrow tube at its mouth. The open end of the tube is kept in a beaker containing water. When the bottle is heated, bubbles of air are seen escaping into water. Explain the reason.

Q32) Which of the following will expand more, when heated to the same temperature: (a) solid (b) liquid and (c) gas?

Q33) Describe an experiment to show that the same volume of different liquids heated to the same rise in temperature expand by different amounts.

Q34) 100 ml of each of the following liquid is heated from 10°C to 50°C. Which will expand more (a) water (b) benzene (c) alcohol?

Q35) Water is heated from 0°C to 4°C. Will it expand?

Q36) What do you mean by anomalous behaviour of water?

Q37) How does the density of a substance (solid, liquid and gas ) change on heating?

Q38) An iron washer is heated.

(a) State the effect on its mass.

(b) State the effect on its internal diameter

(c) State the effect on its external diameter

(d) State the effect on its density.