Following figure shows $P-T$ graph for four processes $A, B, C$ and $D$. Select the correct alternative.

The volume of air increases by $5\%$ in its adiabatic expansion. The percentage decrease in its pressure will be ...... $\%$

Monoatomic, diatomic and triatomic gases whose initial volume and pressure are same, are compressed till their volume becomes half the initial volume.

An ideal gas undergoes four different processes from the same initial state as shown in the figure below. Those processes are adiabatic, isothermal, isobaric and isochoric. The curve which represents the adiabatic process among $1,2,3$ and $4$ is

Consider that an ideal gas ($n$ moles) is expanding in a process given by $P = f (V)$, which passes through a point $(V_0, \,p_0)$. Show that the gas is absorbing heat at $(p_0,\, V_0)$ if the slope of the curve $P = f (V)$ is larger than the slope of the adiabatic passing through $(p_0,\, V_0)$.

Write the expression of work for an ideal gas in isobaric process.