$\Delta W = 0$,for the process

The pressure $P$ of an ideal diatomic gas varies with its absolute temperature $T$ as shown in the figure. The molar heat capacity of the gas during this process is ........... $R$ [$R$ is the gas constant].

Volume versus temperature graph of two moles of helium gas is as shown in figure. The ratio of heat absorbed and the work done by the gas in process $1-2$ is

Which one of the following statements is wrong for an isobaric process?

The thermodynamic process in which the work done on or by the gas is zero is:

Which of the following relations is correct for an isochoric process?