Q. Select the correct alternative :
(a) In evaporation :
(i) all molecules of liquid begin to escape out
(ii) only the molecules at the surface escape out
(iii) the temperature of the liquid rises by absorbing heat from surroundings.
(iv) the molecules get attracted within the liquid.
(b) The rate of evaporation of a liquid increases when :
(i) the temperature of liquid falls
(ii) the liquid is poured in a vessel of less surface area
(iii) air is blown above the surface of the liquid
(iv) humidity increases.
(c) During boiling or vaporization :
(i) all molecules take part
(ii) temperature rises
(iii) no heat is absorbed
(iv) the average kinetic energy of molecules increases.
(d) The boiling point of a liquid is increased by :
(i) increasing the volume of liquid
(ii) increasing the pressure on the liquid.
(iii) adding ice to the liquid
(iv) decreasing pressure on the liquid.
(e) Two rods A and B of the same metal, but of length 1 m and 2 m respectively, are heated from 0∘ to 100∘C. Then :
(i) both the rods A and B elongate the same
(ii) the rod A elongates more than the rod B
(iii) the rod B elongates more than the rod A
(iv) the rod A elongates, but the rod B contracts.
(f) Two rods A and B of the same metal, same length, but one solid and the other hollow, are heated to the same rise in temperature. Then :
(i) the solid rod A expands more than the hollow rod B
(ii) the hollow rod B expands more than the solid rod A
(iii) the hollow rod B contracts, but the solid rod A expands
(iv) both the rods A and B expand the same.
(g) A given volume of alcohol and the same volume of water are heated from the room temperature to the same temperature then :
(i) alcohol contracts, but water expands
(ii) water contracts, but alcohol expands
(iii) water expands more than alcohol
(iv) alcohol expands more than water.
(h) The increase in length of a metal rod depends on :
(i) the initial length of the rod only
(ii) the rise in temperature only
(iii) the material of rod only
(iv)all the above three factors.
(i) The correct statement is :
(i) Iron rims are cooled before they are placed on the cart wheels.
(ii) A glass stopper gets tightened on warming the neck of the bottle.
(iii) Telephone wires sag in winter, but become tight in summer.
(iv) A little space is left between two rails on a railway track.
