For a certain reaction $\Delta \mathrm{H}=-225 \mathrm{~kJ}$ and $\Delta S=-150 \mathrm{JK}^{-1}$. Find the temperature so that $\Delta G$ is zero.

Calculate the ionisation constant of $0.08 \mathrm{~mol} \mathrm{dm}{ }^{-3}$ of a monobasic acid having $\mathrm{pH}=2$.

What is the number of moles of ' C ' and ' H ' atoms respectively present in n mole molecule represented by following structure?

Identify the product obtained when nitro ethane is treated with $\mathrm{Sn}-\mathrm{HCl}$ under ideal conditions.