200 ml of 1M ${\displaystyle H_{2}S{O}_4}$, 300 ml 3M HCl and 100 ml of 2M HCI are mixed and made up to 1 litre. The proton concentration in the resulting solution is

Proton concentration of 200 ml of 1M ${\displaystyle H_{2}S{O}_4}$(2H⁺ ions)= VN=0.2(l)$\times$1$\times$2=0.4

Proton concentration of 300 ml of 3M HCl = 0.3$\times$3=0.9

Proton concentration of 100 ml of 2M HCl = 0.1$\times$2=0.2

Final volume of sol. = 1l

proton concentration in the resulting solution=$\frac{0.4+0.9+0.2}{1}=1.5\mathrm{M}$