Which of these elements has an atom with the most stable outer electron configuration? * Cl Ca Ne Na

Neon (Ne) has the most stable outer electron configuration because the outer electron is completely filled and it has octet structure

Explanation:

The configuration of these elements is as follows;

Cl₁₇ = 2, 8,7 (the outer electron is 7)

Ca₂₀ = 2,8,8,2 (the outer electron is 2)

Ne₁₀ = 2,8 (the outer electron is 8)

Na₁₁ = 2,8,1 (the outer electron is 1)

Based on the outer electron value above, Neon (Ne) has the most stable outer electron configuration because the outer electron is completely filled and it has octet structure.