$2.2016 \ g$ of acetaldehyde produced $13.95 \ kcal$ of heat on combustion in $O_2$. Calculate the heat of combustion of $CH_3CHO$ in $kcal \ mol^{-1}$.

The heat of combustion of carbon monoxide at constant volume and at $17 \ ^oC$ is $-283.3 \ kJ$. Calculate its heat of combustion at constant pressure in $kJ$. $(R = 8.314 \ J \ K^{-1} \ mol^{-1})$ (in $.5$)

Calculate the enthalpy of formation of ethylene in $kJ\,mol^{-1}$ from the following data:
$C_{(graphite)} + O_{2(g)} \to CO_{2(g)} ; \Delta H = -393.5\,kJ$
$H_{2(g)} + 1/2 O_{2(g)} \to H_2O_{(l)} ; \Delta H = -286.2\,kJ$
$C_2H_{4(g)} + 3 O_{2(g)} \to 2 CO_{2(g)} + 2 H_2O_{(l)} ; \Delta H = -1410.8\,kJ$

$XeF_{2(g)} + H_{2(g)} \to 2HF_{(g)} + Xe_{(g)}$,$\Delta H^o = -430 \ kJ$
Bond energy:
$H-H = 435 \ kJ/mol$
$H-F = 565 \ kJ/mol$
Calculate the average bond energy of the $Xe-F$ bond in $kJ/mol$.

The molar enthalpies of combustion of $C_2H_{2(g)},$ $C$ (graphite) and $H_{2(g)}$ are $-1300,$ $-394$ and $-286 \ kJ \ mol^{-1},$ respectively. The standard enthalpy of formation of $C_2H_{2(g)}$ is.......$kJ \ mol^{-1}$

The heat of solution of $Na_2SO_{4(s)}$ and $Na_2SO_4 \cdot 10H_2O_{(s)}$ are $-2.34 \ kJ \ mol^{-1}$ and $78.87 \ kJ \ mol^{-1}$ respectively. The heat of hydration of $Na_2SO_{4(s)}$ is: