What is the $pH$ of a solution containing $4.62 \times 10^{-4} \ M \ H^{+}$ ions?

Which of the following has a $pH$ of $12$?

$75 \ mL$ of $0.2 \ M \ HCl$ is mixed with $25 \ mL$ of $1 \ M \ HCl$. To this solution,$300 \ mL$ of distilled water is added. What is the $pH$ of the resultant solution?

What will be the concentration of $H^{+}$ ions in a solution prepared by dissolving $4 \ g$ of $NaOH$ in $100 \ mL$ of water at $25 \ ^{\circ}C$?

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?

Assuming complete dissociation,the $pH$ of a $0.01 \, M$ $NaOH$ solution is equal to