When $1 \ g$ equivalent of a strong acid reacts with a strong base,the heat released is $13.5 \ kcal$. When $1 \ g$ equivalent of $H_2A$ is completely neutralized against a strong base,$13 \ kcal$ is released. When $1 \ g$ equivalent of $B(OH)_2$ is completely neutralized against a strong acid,$10 \ kcal$ of heat is released. Calculate the enthalpy change when $1 \ mole$ of $H_2A$ is completely neutralized by $B(OH)_2$ in $kcal$.

The enthalpies of combustion of $S_{(s)}$ and $H_{2(g)}$ are $-300 \ kcal \ mol^{-1}$ and $-290 \ kcal \ mol^{-1}$ respectively. Given the following reactions:
$SO_{3(g)} + H_2O_{(l)} \rightarrow H_2SO_{4(l)}$; $\Delta H = -130 \ kcal \ mol^{-1}$
$SO_{2(g)} + 1/2 O_{2(g)} \rightarrow SO_{3(g)}$; $\Delta H = -100 \ kcal \ mol^{-1}$
$S_{(s)} + O_{2(g)} \rightarrow SO_{2(g)}$; $\Delta H = -300 \ kcal \ mol^{-1}$
$H_{2(g)} + 1/2 O_{2(g)} \rightarrow H_2O_{(l)}$; $\Delta H = -290 \ kcal \ mol^{-1}$
The enthalpy of formation of $H_2SO_{4(l)}$ is:

$11.0 \ L$ of an ideal gas at a constant external pressure of $5 \ atm$ is compressed isothermally to a final volume of $1 \ L$. The heat absorbed and work done,respectively,during this compression (in $L \ atm$) are:

Calculate $\Delta H_f^o$ of $SiH_2$ from the following reactions:
$Si_2H_{6(g)} + H_{2(g)} \to 2SiH_{4(g)}, \Delta H = -11.7 \ kJ/mol$
$SiH_{4(g)} \to SiH_{2(g)} + H_{2(g)}, \Delta H = +239.7 \ kJ/mol$
$\Delta H_f^o(Si_2H_{6(g)}) = 80.3 \ kJ/mol$

For the gas phase reaction,$PCl_{5(g)} \rightleftharpoons PCl_{3(g)} + Cl_{2(g)}$,which of the following conditions are correct?

Which of the following statements or relationships is not correct in thermodynamic changes?