The standard molar heat of formation of ethane,$CO_2$,and water $(l)$ are respectively $-21.1$,$-94.1$,and $-68.3 \ kcal$. The standard molar heat of combustion of ethane will be $kcal$.

$A$ thermodynamic cycle in the pressure $(p)-$ volume $(V)$ plane is given below. $A B$ and $C D$ are isothermal processes while $B C$ and $D A$ are adiabatic processes. The same cycle in the temperature $(T) -$ entropy $(S)$ plane is

The heat evolved during the combination of $24 \, g$ of $C$ and $128 \, g$ of $S$ according to the reaction $C + 2S \to CS_2$ with $\Delta H = 22.0 \, kcal$ is:

An ideal gas is expanded from $(p_1, V_1, T_1)$ to $(p_2, V_2, T_2)$ under different conditions. The correct statement$(s)$ among the following is(are):
[$A$] The work done on the gas is maximum when it is compressed irreversibly from $(p_2, V_2)$ to $(p_1, V_1)$ against constant pressure $p_1$.
[$B$] The work done by the gas is less when it is expanded reversibly from $V_1$ to $V_2$ under adiabatic conditions as compared to that when expanded reversibly from $V_1$ to $V_2$ under isothermal conditions.
[$C$] The change in internal energy of the gas is $(i)$ zero,if it is expanded reversibly with $T_1=T_2$,and $(ii)$ positive,if it is expanded reversibly under adiabatic conditions with $T_1 \neq T_2$.
[$D$] If the expansion is carried out freely,it is simultaneously both isothermal as well as adiabatic.

For the combustion of $1 \ mol$ of liquid benzene at $298 \ K$,the heat of reaction at constant pressure is $-3268 \ kJ \ mol^{-1}$. What is the heat of combustion at constant volume? $(R = 8.314 \times 10^{-3} \ kJ \ K^{-1} \ mol^{-1})$

Consider the $P-V$ (pressure-volume) diagram given below,where an ideal gas is reversibly converted from state $X$ to state $Y$. Among the following,which is the correct $T-S$ (temperature-entropy) diagram corresponding to this process?