

Explanation
(a)
A mass of dry air is entrappedin a uniform capillary tube, sealed at one end, by means of a mercury pellet. Both the tube and thermometer are then firmly attacheda half-meter rule and placed in a water bathas shown above. The water is stirred and its temperature \(\theta_{1}\)at a steady state is noted. The corresponding length, \(L_{1}\) of the entrapped air is also noted and recorded. The water is gradually heated and stirred uniformly until another steady temperature, \(\theta_{2}\)is attained and recorded. The corresponding length, \(L_{2}\) of the air column in the capillary tube is again read and recorded. The experiment is repeated to obtain more sets of readings. A graph of L against \(\theta\)is plotted as shown.

Deduction: Since the volume V of the tube is proportional to its length, L the graph shows that the volume of the entrapped air increases (directly) with increase in temperature at constant pressure.
Precautions: Dry air must be used. Also, error ofparallax in reading thermometer and meter rule avoided.
(b) \(S = \frac{V_{1} - V_{0}}{V_{0} \theta}\)
= \(\frac{18.7 - 13.7}{13.7 \times 100}\)
= \(\frac{5}{1370}\)
= \(3.65 \times 10^{-3} K^{-1}\)
(c) As temperature increases the kinetic energies the molecules increase and they bombard the wall the container at a faster rate since their velocities hasincreased. To keep the rate of change of momentum per unit area (i.e pressure) the same, the molecules will have to travel longer distances betweon collision This implies increase in volume.

