The variation of pressure with volume of the gases at different temperatures can be graphically represented as shown in figure. On the basis of this graph answer the following questions.

1.  How will the volume of a gas change if its pressure is increased at constant temperature?

2.  At a constant pressure, how will the volume of a gas change if the temperature is increased from 200 K to 400 K?


(i) In accordance to Boyle's law, pressure of a gas is inversely proportional to its volume if temperature is kept constant. Thus, the volume of a gas will decrease if the pressure on the gas is increased keeping the temperature constant. e.g., at 200 K when pressure increases from p1 to p2, volume of the gas decreases, V2<V1.
(ii) In accordance to charles law, volume of a gas is directly proportional to its temperature if pressure is kept constant.
Thus, on increasing temperature, the volume of a gas will increase if pressure is kept constant.
At constant p when we increase the temperature from 200 K to 400 K, the volume of the gas increases, V4>V3.