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

For an isochoric process,if $T_1 = 27 \, ^\circ C$ and $T_2 = 127 \, ^\circ C$,then $P_1 / P_2 = \dots$

The ratio of work done by an ideal monoatomic gas to the heat supplied to it in an isobaric process is

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, $\gamma = \frac{C_p}{C_v}$):

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

One mole of an ideal gas is contained within a cylinder by a frictionless piston and is initially at temperature $T$. The pressure of the gas is kept constant while it is heated and its volume doubles. If $R$ is the molar gas constant,the work done by the gas in increasing its volume is