Answer question in one word or one sentence.
In which one of `NH_3` and `NH_4^+` does the N atom carry a lone pair of electrons?

Explanation

**Step-by-Step Solution:**

1. **Identify the Compounds**: We are comparing two compounds: NH₃ (ammonia) and NH₄⁺ (ammonium ion).

2. **Determine the Valence Electrons of Nitrogen**: Nitrogen has 5 valence electrons.

3. **Draw the Lewis Structure for NH₃**:
- In NH₃, nitrogen forms three bonds with three hydrogen atoms.
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