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.

In the following schematic diagram for the preparation of hydrogen gas as shown in the Figure,what would happen if the following changes are made?
$(a)$ In place of zinc granules,the same amount of zinc dust is taken in the test tube.
$(b)$ Instead of dilute sulphuric acid,dilute hydrochloric acid is taken.
$(c)$ In place of zinc,copper turnings are taken.
$(d)$ Sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated.

Which substance is added to the soil to neutralize acidic soil?

$(i)$ State the purpose of developing $pH$ scale.
$(ii)$ Mention the $pH$ range for acids.
$(iii)$ What is the $pH$ of acid rain and how it affects the aquatic life?

Which of the following is not an oxide of metal?

In which form do $H^{+}$ (hydrogen) ions exist in water?