$2.1 \ g$ of $Fe$ combines with $S$ evolving $3.77 \ kJ$. The heat of formation of $FeS$ in $kJ/mol$ is

The enthalpy of neutralization of a strong acid by a strong base is $-57.32 \ kJ/mol$. The enthalpy of formation of water is $-285.84 \ kJ/mol$. The enthalpy of formation of hydroxyl ion is......$kJ/mol$. (Assume $\Delta H_{f}^{\circ}(H^{+}_{(aq)}) = 0 \ kJ/mol$)

Given that bond energies of $H-H$ and $Cl-Cl$ are $430 \ kJ \ mol^{-1}$ and $240 \ kJ \ mol^{-1}$ respectively and $\Delta H_f$ for $HCl$ is $-90 \ kJ \ mol^{-1},$ the bond enthalpy of $HCl$ is ............... $kJ \ mol^{-1}$.

Which of the following reactions represents the standard heat of formation of the product?

Which thermochemical reaction is correct?

If bond energy for $H_{2(g)}$,$Br_{2(g)}$ and $HBr_{(g)}$ is $433$,$192$ and $364 \ kJ \ mol^{-1}$ respectively,then $\Delta H^o$ for the reaction,$H_{2(g)} + Br_{2(g)} \to 2HBr_{(g)}$ is......$kJ$.