When handling bromine, it is always advisable to have this in order to stop its action.

• A. Ammonia water
• B. Magnesium hydroxide
• C. Water
• D. Spirit of ammonia

Answer: (A)

Bromine is a very reactive oxidizer, so you want something that can quickly neutralize or quench its reactivity. Aqueous ammonia (ammonia water) does exactly that: it reacts with bromine to form stable salts, effectively removing bromine from the scene and stopping its action. This makes ammonia water the quickest and most practical way to quench bromine among the options.

Water by itself only dilutes bromine and doesn’t neutralize its reactive species, so it’s not as effective. Magnesium hydroxide is a solid base and would be slower and less convenient for rapid quenching. Spirit of ammonia (ammonia in ethanol) is not as reliable a quenching medium as aqueous ammonia and introduces unnecessary flammability concerns.