A mixture of hydrogen and chlorine kept in a closed flask at constant temperature was irradiated with scattered light. After a certain time the chlorine content decreased by 20 $$\%$$ compared with the starting mixture and the resulting mixture had 60 volume $$\%$$ chlorine, 10 volume $$\%$$ hydrogen and 30 volume $$\%$$ hydrogen chloride. Determine the composition of the initial gaseous mixture.

A

$$\mathrm{Cl_2}$$ = 60 $$\%$$, $$\mathrm{H_2}$$ = 40 $$\%$$

B

$$\mathrm{H_2}$$ = 60 $$\%$$, $$\mathrm{Cl_2}$$ = 40 $$\%$$

C

$$\mathrm{Cl_2}$$ = 45 $$\%$$, $$\mathrm{H_2}$$ = 55 $$\%$$

D

$$\mathrm{H_2}$$ = 25 $$\%$$, $$\mathrm{Cl_2}$$ = 75 $$\%$$