What is the $H_{3}O^{+}$ ion called?

Name the acid and base from which the following salts have been formed:
$(i)$ Sodium acetate.
$(ii)$ Ammonium chloride.

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

The $pH$ scale is applicable to which of the following?

If the $pH$ of an aqueous solution is $6$,then its $pOH$ is:

$(a)$ Identify the acid and the base whose combination forms the common salt that you use in your food. Write its formula and chemical name of this salt. Name the source from where it is obtained.
$(b)$ What is rock salt? Mention its colour and the reason due to which it has this colour.
$(c)$ What happens when electricity is passed through brine? Write the chemical equation for it.