WAEC Chemistry 2018 Paper

Concept:Oxidation involves loss of electrons, shown by an increase in oxidation number.Explanation:When zinc is placed in $\mathrm{AgNO}_3$ solution, a displacement reaction occurs.The reaction is:$$\mathrm{Zn} + 2\mathrm{AgNO}_3 \rightarrow \mathrm{Zn(NO_3)}_2 + 2\mathrm{Ag}$$In the reactant, zinc has an oxidation number of $0$.In the product $\mathrm{Zn(NO_3)}_2$, zinc has an oxidation number of $+2$.Since the oxidation number increases from $0$ to $+2$, zinc loses electrons and is oxidised.Answer:A. oxidised