Calculate the heat of formation of $HCl$ gas from the following reaction: $H_{2(g)} + Cl_{2(g)} \rightarrow 2 HCl_{(g)} ; \Delta H = -194 \ kJ$

The enthalpy change for the reaction,$H_{2(g)} + C_2H_{4(g)} \to C_2H_{6(g)}$ is $......$ $kcal \ mol^{-1}$. The bond energies are,$[e_{H-H} = 103, e_{C-H} = 99, e_{C-C} = 80]$ and $[e_{C=C} = 145] \ kcal \ mol^{-1}$.

The standard enthalpy of formation $(\Delta_f H^{\circ})$ of ammonia is $-46.2 \ kJ \ mol^{-1}$. What is the $\Delta_r H^{\circ}$ of the following reaction?
$N_{2(g)} + 3H_{2(g)} \rightarrow 2NH_{3(g)}$

If $C_{(s)} + O_{2(g)} \rightarrow CO_{2(g)}$,$\Delta H = -X$,and $CO_{(g)} + \frac{1}{2} O_{2(g)} \rightarrow CO_{2(g)}$,$\Delta H = -Y$,calculate $\Delta_f H$ for $CO_{(g)}$ formation.

Given that $:$
$2 C_{(s)} + 2 O_{2_{(g)}} \rightarrow 2 CO_{2_{(g)}} ; \Delta H = -787 \ kJ$
$H_{2_{(g)}} + \frac{1}{2} O_{2_{(g)}} \rightarrow H_2 O_{(l)} ; \Delta H = -286 \ kJ$
$C_2 H_{2_{(g)}} + \frac{5}{2} O_{2_{(g)}} \rightarrow 2 CO_{2_{(g)}} + H_2 O_{(l)} ; \Delta H = -1301 \ kJ$
The heat of formation of acetylene will be $:-$

The heats of combustion of yellow phosphorus and red phosphorus are $-9.91 \, kJ$ and $-8.78 \, kJ$ respectively. The heat of transition for the conversion of yellow phosphorus to red phosphorus will be ...... $kJ$?