A substance L reacts with NH$_4$NO$_{3(aq)}$ to generate ammonia gas. L is likely to be

Analyze the question: Ammonium nitrate (NH₄NO₃) is an ammonium salt. We need a substance that reacts with it to release ammonia gas (NH₃).

Concept: Ammonium salts react with alkalis (strong bases) to liberate ammonia gas. This is the standard laboratory test for the ammonium ion (NH₄⁺):

NH₄⁺ + OH⁻ → NH₃ + H₂O

The reaction is usually warmed gently, and the ammonia is recognised by its pungent smell and its ability to turn damp red litmus paper blue.

Solution:

• A. HCl: an acid. It cannot remove H⁺ from NH₄⁺, so there is no reaction and no ammonia.
• B. NaOH: a strong base. It supplies OH⁻, which takes H⁺ from NH₄⁺ and releases NH₃:

NH₄NO₃ + NaOH → NaNO₃ + H₂O + NH₃↑

• C. CH₃COOH: a weak acid, so no ammonia is formed.
• D. CaSO₄: a neutral salt. It is not basic, so it does not liberate ammonia.

Answer: The substance L is NaOH, which is option B.

Tip: Remember "Ammonium salt + alkali → ammonia gas". Whenever a question asks what releases ammonia from an ammonium salt, look for the base or alkali (NaOH, KOH, Ca(OH)₂) and ignore the acids and neutral salts.