WAEC Chemistry 2021 Paper

Concept:Group VII elements are halogens, which act as oxidising agents and exist as diatomic molecules.Explanation:Halogens show different physical states: $\mathrm{F_2}$ and $\mathrm{Cl_2}$ are gases, $\mathrm{Br_2}$ is a liquid, and $\mathrm{I_2}$ is a solid.Therefore, option A is not correct.Halogens gain electrons readily, so they are strong oxidising agents, not strong reducing agents.Therefore, option B is not correct.Down the group, atomic size increases and electron gain becomes less favourable, so their reactivity decreases.Therefore, option C is correct.Halogens exist as diatomic molecules such as $\mathrm{F_2}$, $\mathrm{Cl_2}$, $\mathrm{Br_2}$, and $\mathrm{I_2}$, so option D is not correct.Answer:C. their reactivity decreases down the group