Calculate the difference between heat of combustion of carbon monoxide gas at constant pressure and at constant volume at $27^{\circ} C$ (in $cal$)? $(R = 2 \ cal \ K^{-1} \ mol^{-1})$

Heat of combustion of $CH_4, C_2H_4$ and $C_2H_6$ are $-890, -1411$ and $-1560 \ kJ/mol$ respectively. Which has the lowest calorific value?

Enthalpy of formation of $CO_{2(g)}$,$H_2O_{(l)}$ and $C_6H_{12}O_{6(s)}$ are $-393$,$-286$ and $-1170 \ kJ \ mol^{-1}$ respectively. The quantity of heat liberated when $18 \ g$ of $C_6H_{12}O_{6(s)}$ is burnt completely in oxygen is (in $kJ$)

Enthalpy of neutralisation of acetic acid by $NaOH$ is $-50.6 \ kJ/mol$ and the heat of neutralisation of a strong acid with a strong base is $-55.9 \ kJ/mol$. What is the value of $\Delta H$ for the ionisation of $CH_3COOH$ in $kJ/mol$?

One gram sample of $NH_4NO_3$ is decomposed in a bomb calorimeter. The temperature of the calorimeter increases by $6.12 \ K$. The heat capacity of the system is $1.23 \ kJ/K$. What is the molar heat of decomposition for $NH_4NO_3$ in $kJ/mol$?

The free energy change for the following reactions are given below:
$C_2H_{2(g)} + \frac{5}{2}O_{2(g)} \to 2CO_{2(g)} + H_2O_{(l)}; \Delta G^o = -1234 \ kJ$
$C_{(s)} + O_{2(g)} \to CO_{2(g)}; \Delta G^o = -394 \ kJ$
$H_{2(g)} + \frac{1}{2}O_{2(g)} \to H_2O_{(l)}; \Delta G^o = -237 \ kJ$
What is the standard free energy change for the reaction $H_{2(g)} + 2C_{(s)} \to C_2H_{2(g)}$ in $kJ$?