Classify each of the following as a physical or a chemical change. Give reasons.
$(a)$ Drying of a shirt in the sun.
$(b)$ Rising of hot air over a radiator.
$(c)$ Burning of kerosene in a lantern.
$(d)$ Change in the colour of black tea on adding lemon juice to it.
$(e)$ Churning of milk cream to get butter.

(A) Physical changes: $(a), (b), (e)$. These are physical changes because no new substance is formed,and the chemical composition remains the same.
Chemical changes: $(c), (d)$. These are chemical changes because new substances are formed with different chemical properties. Burning of kerosene involves a combustion reaction,and adding lemon juice to tea causes a chemical reaction between the acid in the lemon and the pigments in the tea.