For the reactions,$C + O_2 \to CO_2; \Delta H = -393 \ J$
$2Zn + O_2 \to 2ZnO; \Delta H = -412 \ J$

Find the enthalpy of neutralisation of $NH_4OH$ and $HCN$ in aqueous solution if the enthalpy of ionisation of $NH_4OH$ and $HCN$ are $7 \ kJ/mol$ and $8 \ kJ/mol$ respectively. Also,the enthalpy of neutralisation of $H^{+}$ and $OH^{-}$ is $-57.3 \ kJ/mol$.

The quantity of heat (in $J$) required to raise the temperature of $1.0 \, kg$ of ethanol from $293.45 \, K$ to the boiling point and then change the liquid to vapor at that temperature is closest to
[Given,boiling point of ethanol $351.45 \, K$. Specific heat capacity of liquid ethanol $2.44 \, J \, g^{-1} \, K^{-1}$. Latent heat of vaporisation of ethanol $855 \, J \, g^{-1}$ ]

The heat of reaction for $C_6H_{12}O_{6(s)} + 6O_{2(g)} \to 6CO_{2(g)} + 6H_2O_{(l)}$ at constant pressure is $-651 \, kcal$ at $17 \, ^oC$. Calculate the heat of reaction at constant volume at $17 \, ^oC$ in $kcal$.

If $\Delta G$ and $\Delta S$ for the reaction $A_{(g)} \rightarrow B_{(g)} + 2C_{(g)}$ at $2000 \ K$ are $-40 \ kJ \ mol^{-1}$ and $0.22 \ kJ \ K^{-1} \ mol^{-1}$ respectively,the change in internal energy for the same reaction approximately (in $kJ \ mol^{-1}$) is

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