Match the atomic number 2, 4, 8, 15 and 19 with the following:
A gaseous element with valency 2.

Explanation

To solve the question of matching the atomic number with the description "A gaseous element with valency 2," we can follow these steps:

### Step 1: Understand Valency
Valency is defined as the ability of an atom to lose or gain electrons to achieve a stable electronic configuration, often resembling that of noble gases. For this question, we are looking for an element that can either lose or gain 2 electrons.

**Hint:** Remember that elements can achieve stability by either losing or gaining electrons.

### Step 2: Identify the Atomic Numbers
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