Which from following elements exhibits usual tendency to undergo reduction?

According to reaction,

$$\mathrm{Mg}(s)+2 \mathrm{HCl}(a q) \longrightarrow \mathrm{MgCl}_2(a q)+\mathrm{H}_2(g) \uparrow .$$

Calculate the mass of $$\mathrm{Mg}$$ required to liberate $$4.48 \mathrm{~dm}^3 \mathrm{~H}_2$$ at STP?

(Molar mass of $$\mathrm{Mg}=24 \mathrm{~g} \mathrm{~mol}^{-1}$$)

A closed container contains mixture of non-reacting gases $$A$$ and $$B$$. Partial pressure of $$A$$ and $$B$$ are 4.5 bar and 5.5 bar respectively. Find mole fractions of $$A$$ and $$B$$ respectively?

Which from following compounds is obtained when toluene is treated with $$\mathrm{CrO}_2 \mathrm{Cl}_2$$ in presence of $$\mathrm{CS}_2$$ followed by acid hydrolysis?