Which relation is correct for an isochoric process?

The change in internal energy of a mass of gas, when the volume changes from $V$ to $2V$ at constant pressure $P$ is (where $\gamma$ is the ratio of specific heat at constant pressure to that at constant volume, $\gamma = \frac{C_p}{C_v}$):

Calculate the work done when the volume of a gas increases by $0.25\,m^3$ at a constant pressure of $10^3\,N/m^2$.

$A$ quantity of heat $Q$ is supplied to a monoatomic ideal gas which expands at constant pressure. The fraction of heat that goes into work done by the gas is

In an isochoric process,if $t_1 = 27^{\circ}C$ and $t_2 = 127^{\circ}C$,then $\frac{P_1}{P_2}$ will be equal to [$P_1$ and $P_2$ are the pressures at $t_1^{\circ}C$ and $t_2^{\circ}C$ respectively].

If $\gamma$ is the ratio of molar specific heat at constant pressure to molar specific heat at constant volume for a gas,find the change in internal energy of $1 \, mol$ of the gas when its volume changes from $V$ to $2V$ at constant pressure $P$.