Outermost electronic configurations of four elements A, B, C, D are:

(A) 3s
(B) 3s3p
(C) 3s3p
(D) 3s3p

The correct order of first ionization enthalpy for them is:

Question

Outermost electronic configurations of four elements A, B, C, D are:

(A) 3s
(B) 3s3p
(C) 3s3p
(D) 3s3p

The correct order of first ionization enthalpy for them is:

Canvas Classes · Accepted Answer

Strategy:
 Identify the elements based on their configurations and apply  trends in Period 3. Consider configuration stability (half-filled  vs. ).

Step 1: Identify the elements
- (A) : Magnesium ()
- (B) : Aluminum ()
- (C) : Phosphorus ()
- (D) : Sulfur ()

Step 2: Order by Ionization Enthalpy
- General trend:  and  (incorrect).
- Anomalies:
  - : Breaking a filled -subshell is harder.
  - : Half-filled -subshell is more stable than  where pairing causes repulsion.

Step 3: Final Order
  B <

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