Write true or false for the following statement:
The insoluble substance formed during a chemical reaction is known as a precipitate.

Explain the type of reactions represented by the following equations:
$(i)$ $CaO + CO_2 \longrightarrow CaCO_3$
$(ii)$ $2Na + 2H_2O \longrightarrow 2NaOH + H_2$

Which substance is formed when ammonia gas reacts with hydrogen chloride gas?

State the kind of chemical reactions in the following examples:
$(a)$ Digestion of food in the stomach
$(b)$ Combustion of coal in air.

"$A$ solution of potassium chloride when mixed with silver nitrate solution, an insoluble white substance is formed".
$(i)$ Translate the above statement into a chemical equation.

$2 \, g$ of ferrous sulphate crystals are heated in a boiling tube.
$(i)$ State the colour of ferrous sulphate crystals both before heating and after heating.
$(ii)$ Name the gases produced during heating.
$(iii)$ Write the chemical equation for the reaction.