When $10^{-8} \ mol$ of $HCl$ is dissolved in one litre of water,the $pH$ of the solution will be

Five solutions of $KOH$ are prepared as follows: $1st \to 0.1 \ mol$ in $1 \ L$,$2nd \to 0.2 \ mol$ in $2 \ L$,$3rd \to 0.3 \ mol$ in $3 \ L$,$4th \to 0.4 \ mol$ in $4 \ L$,$5th \to 0.5 \ mol$ in $5 \ L$. What is the $pH$ of the resulting mixture?

Equal volumes of three acid solutions of $pH$ $3$,$4$ and $5$ are mixed in a vessel. What will be the $H^{+}$ ion concentration in the mixture in terms of $\times 10^{-4} \ M$?

What is the $pH$ of a $1 \ mM$ solution of $NaOH$?

Which would decrease the $pH$ of $25 \ cm^3$ of a $0.01 \ M$ solution of hydrochloric acid?

Weight of $Ca(OH)_2$ needed to prepare $250 \ mL$ of solution with $pH = 13$. (in $g$)