The enthalpy of $1 \ mol$ of a compound is equal to its ...... (when it is formed from its constituent elements).

Which of the following is an endothermic reaction?

Which of the following acids will release the maximum amount of heat when completely neutralized by a strong base $NaOH$?

Energy required to dissociate $16 \ g$ of $O_{2(g)}$ into free atoms is $x \ kJ$. The value of bond enthalpy of $O=O$ bond is

Which of the following reactions satisfies the following conditions?
$(a)$ Heat of combustion reaction
$(b)$ Heat of formation reaction
$(c)$ An exothermic reaction
$(d)$ Not a neutralization reaction

The enthalpy of combustion at $25\,^{\circ}C$ of $H_2$,cyclohexene $(C_6H_{10})$ and cyclohexane $(C_6H_{12})$ are $-241$,$-3800$ and $-3920 \ kJ/mol$ respectively. The heat of hydrogenation of cyclohexene is.....$kJ/mol$.