With what the internal energy of real gases be determined ?

A diatomic gas $(\gamma=1.4)$ does $200 \mathrm{~J}$ of work when it is expanded isobarically. The heat given to the gas in the process is:

An ideal gas is taken from point $A$ to the point $B,$ as shown in the $P-V$ diagram, keeping the temperature constant. The work done in the process is

A gas taken through cyclic process $ABCA$ is shown in figure. If $2.4\,cal.$ of heat is given in the process, what is value of $J$ …… $J/cal$ (mechanical equivalent of heat)?

When a system is taken from a state $i$ to $f$ along the path $iaf$ (as shown in the figure). $Q = 50\, cal$ and $W = 20\, cal$ ; along path $ibf,$ $Q = 36\, cal.$

$(i)$ What is $W$ along path $ibf$ ?

$(ii)$ If $W = 13$ cal for path $fi$, what is $Q$ for the path $fi$ ?

$(iii)$ Take $E_{int,i} = 10\,\, cal$ then what is $E_{int,f}$ ?