Answer is: formula of phosgene is COCl₂. V = 1.00 L. Vm = 22.4 L/mol. n (phosgene) = V ÷ Vm. n (phosgene) = 1.00 L ÷ 22.4 L/mol = 0.0446 mol. m (phosgene) = 4.42 g. M (phosgene) = m (phosgene) ÷ n (phosgene). M (phosgene) = 4.42 g ÷ 0.0446 mol = 99 g/mol. n (C) : n (O) : n (Cl) = ω (C)/Ar (C) : ω (O)/Ar (O) : ω (Cl)/Ar (Cl).