For the reaction $CO_{(g)} + \frac{1}{2}O_{2_{(g)}} \rightarrow CO_{2_{(g)}}$ at $17^o C$ and constant volume,the heat of reaction is $-67.71 \, K \, cal$. What is the heat of reaction at constant pressure at $17^o C$ in $K \, cal$?

For the hypothetical reaction
$A_{2(g)} + B_{2(g)} \rightleftharpoons 2AB_{(g)}$
$\Delta_r G^o$ and $\Delta_r S^o$ are $20 \ kJ/mol$ and $-20 \ J K^{-1} mol^{-1}$ respectively at $200 \ K$.
If $\Delta_r C_P$ is $20 \ J K^{-1} mol^{-1}$ then $\Delta_r H^o$ at $400 \ K$ is.....$kJ/mol$

One mole of water is converted into steam at $373 \, K$. The heat absorbed at $1 \, atm$ pressure is $40.68 \, kJ$. If the molar volumes of water and steam are $18 \, mL$ and $30600 \, mL$ respectively,find $\Delta U$ for the process in $kJ$.

Calculate the enthalpy change when $50 \ mL$ of $0.01 \ M$ $Ca(OH)_2$ reacts with $25 \ mL$ of $0.01 \ M$ $HCl$. Given that $\Delta H^o$ for neutralization of a strong acid and a strong base is $-13.7 \ kcal \ mol^{-1}$. (Note: The provided value in the prompt $140 \ kcal \ mol^{-1}$ is physically incorrect for neutralization; using standard value $-13.7 \ kcal \ mol^{-1}$ for calculation). (in $kcal$)

$A$ sample of $n$-octane $(1.14 \ g)$ was completely burnt in excess of oxygen in a bomb calorimeter,whose heat capacity is $5 \ kJ \ K^{-1}$. As a result of the combustion reaction,the temperature of the calorimeter increased by $5 \ K$. The magnitude of the heat of combustion of octane at constant volume is $.......... \ kJ \ mol^{-1}$ (nearest integer).

Which among the following are true for an irreversible isothermal expansion of an ideal gas?
$(i)$ $W = -Q$
$(ii)$ $\Delta U = 0$
$(iii)$ $\Delta H \neq 0$
$(iv)$ $\Delta T = 0$