JAMB Chemistry 2020 Paper

Concept:Some gases support combustion because heat decomposes them to release oxygen.Explanation:A brightly glowing splint supplies enough heat to decompose nitrogen(I) oxide.$\mathrm{N}_2\mathrm{O}$ decomposes to nitrogen and oxygen:$$2\mathrm{N}_2\mathrm{O} \xrightarrow{\text{heat}} 2\mathrm{N}_2 + \mathrm{O}_2$$The oxygen released rekindles the brightly glowing splint.A feebly glowing splint is not hot enough to cause this decomposition, so the gas may extinguish it.Among the options, $\mathrm{N}_2\mathrm{O}$ fits this behaviour.Answer:C. $\mathrm{N}_2\mathrm{O}$