Which of the following molecules consist minimum lone pair of electrons in the valence shell of central atom?

What is the SI unit of rate of diffusion for a gas?

Which of the following gases causes depletion in ozone layer?

Find standard enthalpy of formation of ammonia from following reaction.

$$ \mathrm{N}_{2(\mathrm{~g})}+3 \mathrm{H}_{2(\mathrm{~g})} \longrightarrow 2 \mathrm{NH}_{3(\mathrm{~g})} ; \Delta_{\mathrm{r}} \mathrm{H}^0=-92.0 \mathrm{~kJ} $$