Calculate the value of $$\Delta G$$ for following reaction at $$300 \mathrm{~K}$$.

$$\begin{aligned} & \mathrm{H}_2 \mathrm{O}_{(\mathrm{s})} \longrightarrow \mathrm{H}_2 \mathrm{O}_{(l)} \\ & \left(\Delta \mathrm{H}=7 \mathrm{~kJ}, \Delta \mathrm{S}=24.8 \mathrm{~J} \mathrm{~K}^{-1}\right) \end{aligned}$$

What is the oxidation state of carbon in $$\mathrm{CaC}_2$$ and $$\mathrm{K}_2 \mathrm{C}_2 \mathrm{O}_4$$ respectively?

What is the number of moles of water molecules required to prepare n moles of methane from n moles of methyl magnesium iodide?

Which of the following metals is used as catalyst in manufacture of sulphuric acid by contact process?