$pH$ value of a solution,whose hydronium ion concentration is $6.2 \times 10^{-9} \ mol/L$,is

The ionization constant of $0.1$ $M$ weak acid is $1.74 \times 10^{-5}$ at $298$ $K$ temperature. Calculate the $pH$ of its $0.1$ $M$ solution. (in $.88$)

$1.0 \ mol$ of $HCl$ and $1.0 \ mol$ of $CH_3COONa$ are dissolved in water to make a $1 \ L$ solution. What is the concentration of $H^+$ in the solution? ($K_a$ for $CH_3COOH = 1.6 \times 10^{-5}$)

Dissociation constant for a monobasic acid is $10^{-4}$. What is the $pH$ of the monobasic acid? (If $\%$ dissociation $= 2\,\%$)

What is the $pH$ of a $1 \ M$ $CH_3COOH$ solution? Given that the $K_a$ of acetic acid $= 1.8 \times 10^{-5}$.

The degree of ionization of $0.4 \ M$ acetic acid will be $(K_{a} = 1.8 \times 10^{-5})$.