The variation of pressure with volume of a gas at different temperatures can be graphically represented as shown in the figure. On the basis of this graph,answer the following questions:
$(i)$ How will the volume of a gas change if its pressure is increased at constant temperature?
$(ii)$ At a constant pressure,how will the volume of a gas change if the temperature is increased from $200 \ K$ to $400 \ K$?

(N/A) $(i)$ According to Boyle's law,the pressure of a gas is inversely proportional to its volume if the temperature is kept constant. Thus,the volume of the gas decreases if the pressure on the gas increases while keeping the temperature constant. For example,at $200 \ K$,when pressure is increased from $p_{1}$ to $p_{2}$,the volume of the gas decreases,i.e.,$V_{2} < V_{1}$.
$(ii)$ According to Charles's law,the volume of a gas is directly proportional to its temperature if the pressure is kept constant. Thus,on increasing the temperature,the volume of a gas will increase if the pressure is kept constant. At constant $p$,when we increase the temperature from $200 \ K$ to $400 \ K$,the volume of the gas increases,i.e.,$V_{4} > V_{3}$.