Which is expected to have the highest melting point :
`NH_(3),(CH_(3))_(3)N or PH_(3)`? Explain why?

Explanation

To determine which compound has the highest melting point among \( NH_3 \) (ammonia), \( (CH_3)_3N \) (trimethylamine), and \( PH_3 \) (phosphine), we need to analyze the intermolecular forces present in each compound.

### Step-by-Step Solution:

1. **Identify the Compounds and Their Structures**:
- \( NH_3 \) (Ammonia): Contains one nitrogen atom bonded to three hydrogen atoms. The nitrogen atom has a lone pair of electrons.
- \( (CH_3)_3N \) (Trimethylamine): Contains one nitrogen atom bonded to three methyl groups (carbon and hydrogen).
- \( PH_3 \) (Phosphine): Contains one phosphorus atom bonded to three hydrogen atoms.
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