Calcium phosphate is present in tooth enamel. Its nature is

Write true or false for the following statement:
Mixing an acid or base with water results in an increase in the concentration of ions $(H_{3}O^{+} / OH^{-})$ per unit volume.

Write true or false for the following statement:
On the $pH$ scale,we can measure $pH$ from $0$ (very acidic) to $14$ (very alkaline).

Which of the following is a strong acid?

$A$ metal carbonate $X$ on reacting with an acid gives a gas which when passed through a solution $Y$ gives the carbonate back. On the other hand,a gas $G$ that is obtained at anode during electrolysis of brine is passed on dry $Y$,it gives a compound $Z$,used for disinfecting drinking water. Identify $X$,$Y$,$G$ and $Z$.

What is the concentration of $[H_3O^+]$ in distilled water at $298 \; K$?