Question

What is the electronic configuration of third element of group-2 in periodic table?

• A. [Ne] 3S¹
• B. [Ne] 3S²
• C. [Ar] 4S¹
• D. [Ar] 4S²

Hint:

The electronic configuration of magnesium (Mg) is \([ \text{Ar} ] 4s^2\), as it is the third element of group-2.

Answer 1

The Correct Option is D

Step 1: Understanding the element.
The third element of group-2 in the periodic table is magnesium (Mg). The atomic number of magnesium is 12, so its electronic configuration is: \[ \text{Mg: } 1s^2 2s^2 2p^6 3s^2 \] This is equivalent to \([ \text{Ar} ] 4s^2\).
Step 2: Analyzing the options.
(A) [Ne] 3S¹: Incorrect, this is the electronic configuration of sodium (Na), not magnesium.
(B) [Ne] 3S²: Incorrect, this is the configuration of magnesium, but the question asks for the third element of group-2.
(C) [Ar] 4S¹: Incorrect, the correct configuration for magnesium should be \([ \text{Ar} ] 4s^2\).
(D) [Ar] 4S²: Correct — This is the correct electronic configuration for magnesium.
Step 3: Conclusion.
The correct answer is (D) [Ar] 4S².