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:

When a $10^{-6} \ M \ NaOH$ solution is diluted $100$ times,the $pH$ of the diluted solution will be ............ .

Water is added to $1.0 \ mL$ of $0.1 \ M$ $HCl$ solution to make the total volume $50 \ mL$. Calculate the $pH$ change of the solution.

What is the normality of an aqueous solution of $H_2SO_4$ having $pH = 1$ (in $N$)?

Following solutions were prepared by mixing different volumes of $NaOH$ and $HCl$ of different concentrations:
$a. \; 60 \; mL \; \frac{M}{10} \; HCl + 40 \; mL \; \frac{M}{10} \; NaOH$
$b. \; 55 \; mL \; \frac{M}{10} \; HCl + 45 \; mL \; \frac{M}{10} \; NaOH$
$c. \; 75 \; mL \; \frac{M}{5} \; HCl + 25 \; mL \; \frac{M}{5} \; NaOH$
$d. \; 100 \; mL \; \frac{M}{10} \; HCl + 100 \; mL \; \frac{M}{10} \; NaOH$
$pH$ of which one of them will be equal to $1$?

What is the $pH$ of the resulting solution when equal volumes of $0.1 \ M \ NaOH$ and $0.01 \ M \ HCl$ are mixed?