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

$600 \, mL$ of $0.01 \, M \, HCl$ is mixed with $400 \, mL$ of $0.01 \, M \, H_2SO_4$. The $pH$ of the mixture is $....... \times 10^{-2}$. (Nearest integer) [Given $\log 2 = 0.30, \quad \log 3 = 0.48, \quad \log 5 = 0.69, \quad \log 7 = 0.84, \quad \log 11 = 1.04$]

How many liters of water must be added to $1 \ L$ of an aqueous $HCl$ solution with $pH = 1$ to make the $pH$ of the resulting solution equal to $2$ (in $L$)?

If a solution of $10^{-6} \ M \ HCl$ is diluted $100$ times,the $pH$ of the solution is:

The concentration of $H^{+}$ ions in $0.1 \, M \, NaOH$ is .......

The hydroxyl ion concentration of $10^{-2} \ M \ HCl$ is: