$pH$ of a $10 \ M$ solution of $HCl$ is

Calculate the concentration of hydrogen ions $[H^+]$ in the following solutions: $(a)$ $0.001 \ M \ HNO_3$ $(b)$ $0.0001 \ M \ KOH$.

Which of the following has the highest $pH$?

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

$75 \ mL$ 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?

How many moles of $HCl$ must be removed from $1 \ L$ of an aqueous $HCl$ solution to change its $pH$ from $2$ to $3$?