Which of the following is a strong acid?

The physiological reactions occurring in the human body take place in the range of $......\,pH.$

Which of the following are present in a dilute aqueous solution of hydrochloric acid?

$(a)$ 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.

According to the Arrhenius theory,an acid is a hydrogen-containing compound that produces $..........$ in its aqueous solution.

Write true or false for the following statements:
Care must be taken while mixing concentrated nitric acid or sulphuric acid with water. The water must always be added slowly to the acid with constant stirring.