138. Solving a chemistry problem

6. For a gas mixture of mass composition (%): Сl2 - 67; Br2 - 28; O2 - 5, calculate: 1) volumetric composition; 2) partial pressures of the components; 3) the volume of 1 kg of the mixture. The total pressure is 1.013 * 105 Pa. Temperature 373 K.