Which of the following is(are) an endothermic process(es)?
$(i)$ Dilution of sulphuric acid
$(ii)$ Sublimation of dry ice
$(iii)$ Condensation of water vapours
$(iv)$ Evaporation of water

Which among the following is(are) double displacement reaction$(s)$?
$(i)$ $Pb + CuCl_2 \longrightarrow PbCl_2 + Cu$
$(ii)$ $Na_2SO_4 + BaCl_2 \longrightarrow BaSO_4 + 2NaCl$
$(iii)$ $C + O_2 \longrightarrow CO_2$
$(iv)$ $CH_4 + 2O_2 \longrightarrow CO_2 + 2H_2O$

What happens when zinc granules are treated with dilute solutions of $NaCl$ and $NaOH$? Also,write the chemical equations if a reaction occurs.

What happens when hydrogen gas is passed over heated copper oxide $(CuO)$?

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

Translate the following reactions into balanced chemical equations:
$(i)$ Manganese dioxide is heated with aluminium powder.
$(ii)$ Iron is treated with steam.