100 mL of 5 M $\mathrm{NaOH}$ solution (density 1.2 g/ml) added to 200 mL of another $\mathrm{NaOH}$ solution which as a density of 1.5 g/ml and contains 20 mass percent of $\mathrm{NaOH}$. What will be the volume of the gas (at STP) in litres liberated when aluminium reacts with this (final) solution? [Give answer excluding decimal places] The reaction is $\mathrm{Al}+\mathrm{NaOH}+{\mathrm{H}}_2\mathrm{O}⟶{\mathrm{NaAlO}}_2+{\mathrm{H}}_2$ (At. wt. $\mathrm{Na}= 23, \mathrm{O}= 16, \mathrm{H} = 1)$