What is the $pH$ of a $0.001 \, M \, KOH$ solution at $90 \, ^\circ C$ $(K_w = 10^{-12})$?

The $pH$ of $100 \ mL$ of an aqueous solution of a strong acid is $1$. The volume of water to be added to change its $pH$ to $2$ is .......... $mL$.

Given the concentrations of different acids in the following mixtures,which mixture has the highest $pH$?

Given that the dissociation constant for $H_2O$ is $K_w = 1 \times 10^{-14} \ mol^2 \ L^{-2}$,what is the $pH$ of a $0.001 \ M \ KOH$ solution?

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?

The $pH$ of a $10^{-10} \ M \ NaOH$ solution is approximately......