Which of the following has a standard enthalpy of formation equal to zero?

For the reaction $2H_2O_2(\ell) \to 2H_2O(\ell) + O_2(g)$,what is the enthalpy change? Given that the heats of formation of $H_2O_2(\ell)$ and $H_2O(\ell)$ are $-188 \, kJ/mol$ and $-286 \, kJ/mol$ respectively.

Calculate the enthalpy of vaporisation of ethanol if $11.5 \ g$ of ethanol is completely vaporised by supplying $11.8 \ kJ$ of heat.

If the value of $\Delta H$ in a reaction is positive,then the reaction is called

Enthalpy of formation of two compounds $X$ and $Y$ are $-84 \ kJ$ and $-156 \ kJ$ respectively. Which of the following statements is correct?

What is the standard $N \equiv N$ bond enthalpy from the following reaction? $N_{2(g)} + 3H_{2(g)} \longrightarrow 2NH_{3(g)} \quad \Delta H^{\circ} = -83 \ kJ$
Given: $(\Delta H^{\circ}_{(H-H)} = 435 \ kJ \text{ mol}^{-1}, \Delta H^{\circ}_{(N-H)} = 389 \ kJ \text{ mol}^{-1})$