Why common salt `(NaCl)` sometimes appear yellow?

Explanation

To understand why common salt (NaCl) sometimes appears yellow, we can break down the explanation into a series of steps:

### Step 1: Understanding NaCl Structure
Sodium chloride (NaCl) is an ionic compound that forms a crystal lattice structure. In this structure, sodium ions (Na⁺) and chloride ions (Cl⁻) are arranged in a repeating three-dimensional pattern.

**Hint:** Remember that NaCl consists of alternating positive and negative ions in a crystal lattice.

### Step 2: Heating NaCl in Sodium Vapor
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