Chemical Bonding · JEE Main previous year questions

2010 1 question

1. Q642010 · 25 Apr 2010 · Shift 1

   The standard enthalpy of formation of $\mathrm{N}{\mathrm{H}}_3$ is $-46.0\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$. If the enthalpy of formation of ${\mathrm{H}}_2$ from its atoms is $-436\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$ and that of ${\mathrm{N}}_2$ is $-712\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$, the average bond enthalpy of $\mathrm{N}-\mathrm{H}$ bond in $\mathrm{N}{\mathrm{H}}_3$ is :

   1. A.$-964\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$
   2. B.$+352\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$
   3. C.$+1056\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$
   4. D.$-1102\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$
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   Answer: B