V смеси = V (O2) + V (N2) + V (CO2) + V (Cl2) = 40+45+35+18=138 л
φ (О2) = V (O2) / V смеси * 100% = 40 / 138 * 100% = 28,99%
φ (N2) = V (N2) / V смеси * 100% = 45/138*100% = 32,61%
φ (CO2) = V (CO2) / V смеси * 100% = 35/138*100%=25,36%
φ (Cl2) = V (Cl2) / V смеси * 100% = 18/138*100% = 13,04%