What is the weight of oxygen that is required for the complete combustion of 2.8 kg of ethylene?

$$\begin{gathered} \underset{ 28\mathrm{g}}{ {\mathrm{C}}_2{\mathrm{H}}_4}+\underset{ 3\times 32\mathrm{g}}{3{\mathrm{O}}_2}\to 2{\mathrm{CO}}_2+2{\mathrm{H}}_2\mathrm{O} \\ 2.8\times {10}^3\mathrm{g} ? \end{gathered}$$

Mass of oxygen required = $\frac{2.8\times {10}^3}{28}\times 3\times 32=9.6\times {10}^3\mathrm{g}=9.6\mathrm{kg}$