Ammonia as Brønsted-Lowry Base: Proton Acceptance

Steps:

• Recall Brønsted-Lowry base accepts a proton (H⁺) from an acid.
• Examine each reaction for NH₃ gaining H⁺ to form NH₄⁺.
• In option B, NH₃ + H₂O → NH₄⁺ + OH⁻ shows proton transfer from water.
• Confirm other options lack proton acceptance by NH₃.

Why B is correct:

• NH₃ accepts H⁺ from H₂O, forming NH₄⁺, matching Brønsted-Lowry base definition.

Why the others are wrong:

• A: NH₃ acts as nucleophile in substitution with CH₃Br, not proton acceptor.
• C: NH₃ reduces Na to form NaNH₂, behaving as reducing agent.
• D: NH₃ undergoes oxidation by O₂, not acid-base reaction.

Final answer: B