2021 H2 Chem P1 Q19 — Halogenoalkane Solution

The answer is D (neither student is correct).

Student P is not correct. No visible result with warm silver nitrate only shows that no halide ion was released. The compound could be a halogenoarene, but it could equally be any organic compound that contains no halogen or does not release a halide ion, for example an alkane, an alkene or an alcohol. So it is not definitely a halogenoarene.

Student Q is not correct. The compound could still be a halogenoalkane: a fluoroalkane does not undergo hydrolysis because the C-F bond is very strong, and even if \(\text{F}^-\) were released, AgF is soluble in water, so no precipitate would be seen.

• A is wrong: it marks student P as correct, but the result does not prove the compound is a halogenoarene.
• B is wrong: it marks student Q as correct, but a fluoroalkane also gives no visible result.
• C is wrong: neither student is correct, for the reasons above.