$4 \ g$ of $NaOH$ is added in water to form $500 \ mL$ solution at $298 \ K$. What is the $pH$ of the solution? (Molar mass of $NaOH = 40 \ g \ mol^{-1}$)

$600 \, mL$ 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 $\log 2 = 0.30, \quad \log 3 = 0.48, \quad \log 5 = 0.69, \quad \log 7 = 0.84, \quad \log 11 = 1.04$]

The $pH$ of a solution obtained by mixing $50 \ mL$ of $0.4 \ N \ HCl$ and $50 \ mL$ of $0.2 \ N \ NaOH$ is

Calculate the $pH$ of $1.0 \times 10^{-8} \ M \ NaOH$ solution.

The $pH$ of $1 \ N$ $KOH$ solution is:

If $1 \ mL$ of $1 \ M \ HCl$ solution is added to $99 \ mL$ of aqueous solution of $NaCl$,the $pH$ of the solution changes by $X$ units. The value of $X$ is: