$L$ litres of water must be added to $1 \, L$ of an aqueous solution of $HCl$ with a $pH$ of $1$ to create an aqueous solution with $pH$ of $2$?

Assuming complete ionisation,the $pH$ of $0.1\,M\,HCl$ is $1$. The molarity of $H_2SO_4$ with the same $pH$ is (in $,M$)

What is the $pH$ of a solution containing $H^{+}$ ion concentration $2.5 \times 10^{-3} \ mol \ dm^{-3}$? (Given $\log 2.5 = 0.3979$)

What is the $pH$ of a $NaOH$ solution with a concentration of $0.01 \ g \ L^{-1}$?

At $298 \, K$,what is the concentration of hydrogen ions in a $10^{-8} \, M \, HCl$ aqueous solution? $(K_W = 10^{-14})$

When an aqueous solution of a strong acid with $pH = 5$ is mixed with an equal volume of an aqueous solution of a strong acid with $pH = 3$,what will be the $pH$ of the resulting solution?