Figure shows $P-T$ diagram for a given mass of an ideal gas for the process $A\to B.$ During this process, density of the gas is

Figure shows $V-T$ curves for a given mass of an ideal gas at pressures $P_1$ and $P_2.$ Then

The $P-V$ diagram of a gas at constant temperature are drawn. The curve $1$ is for a constant mass $m_1$ and temperature $T_1$ and curve $2$ is for a constant mass $m_2$ and temperature $T_2.$ Select the correct alternative.