Ammonia solution should not be stored with which of the following substances?

• A. Cyclohexane solution
• B. 2-Propanol solution
• C. Acetic acid solution
• D. Sodium hydroxide solution

Answer: (C)

The main idea is that mixing a base with an acid can neutralize the base and change the storage properties, which is unsafe for storage containers. Ammonia solution is a weak base in water, so it should not be stored with acids.

With acetic acid, a neutralization occurs: ammonia reacts with acetic acid to form ammonium acetate. This changes the composition and pH of the solution, and in a sealed container could lead to heat release or salt precipitation, potentially compromising storage safety. That’s why acetic acid is the incompatible partner.

The other substances do not react in a similar way with ammonia. Cyclohexane is immiscible with aqueous ammonia, so there’s no chemical reaction to worry about, just a physical separation. Isopropanol can mix with ammonia without a chemical reaction. Sodium hydroxide is another base, so two bases simply blend together without neutralization or gas formation. In summary, the acid–base neutralization risk makes acetic acid the incompatible choice for storage with ammonia solution.