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NEET Chemistry QUESTION #7383
Question 1
Magnesium reacts with element X (ground state configuration: \(1s^2\,2s^2\,2p^3\)) to form an ionic compound. The simplest formula of this compound is:
  • \(\text{Mg}_2\text{X}\)
  • \(\text{MgX}_2\)
  • \(\text{Mg}_3\text{X}_2\)✔
  • \(\text{Mg}_3\text{X}_2\)
Correct Answer Explanation
Identifying X: \(1s^2\,2s^2\,2p^3\) = 7 electrons → Nitrogen (N)

Nitrogen needs 3 electrons to complete its octet → forms \(\text{N}^{3-}\)
Magnesium loses 2 electrons → forms \(\text{Mg}^{2+}\)

To balance charges: 3 Mg²⁺ provide \(+6\), 2 N³⁻ provide \(-6\)

Formula: \(\text{Mg}_3\text{X}_2\) (like \(\text{Mg}_3\text{N}_2\))