[tex]\text{Volume,}~V = 50 \times 25 \times 8 = 10000~ m^3\\\\\text{Density,}~\rho = 1.2 ~ kg ~m^{-3}\\ \\\\\text{We know that,}\\\\`~~~~~~~\rho = \dfrac{m}{V}\\\\\implies m = \rho V \\\\\implies m = 1.2 \times 10000 = 12000~kg}\\\\\text{Hence the mass of air is 12000 kg.}[/tex]
