A gas undergoes an isothermal process. The specific heat capacity of the gas in the process is:

Two cylinders $A$ and $B$ of equal capacity are connected to each other via a stop cock. A contains an ideal gas at standard temperature and pressure. $B$ is completely evacuated. The entire system is thermally insulated. The stop cock is suddenly opened. The process is: 
1. adiabatic 
2. isochoric 
3. isobaric 
4. isothermal 

The $(P\text{-}V)$ diagram for an ideal gas in a piston-cylinder assembly undergoing a thermodynamic process is shown in the figure. The process is:

$1~\text g$ of water of volume $1~\text{cm}^3$ at $100^\circ \text{C}$ is converted into steam at the same temperature under normal atmospheric pressure $\approx 1\times10^{5}~\text{Pa}.$ The volume of  steam formed equals $1671~\text{cm}^3.$ If the specific latent heat of vaporization of water is $2256~\text{J/g},$ the change in internal energy is:
1. $2423~\text J$ 
2. $2089~\text J$ 
3. $167~\text J$ 
4. $2256~\text J$