Question

Which of the following electronegativity order is incorrect?

• A. Al \( <\) Mg \( <\) B \( <\) N
• B. Al \( <\) Si \( <\) C \( <\) N
• C. Mg \( <\) Be \( <\) B \( <\) N
• D. S \( <\) Cl \( <\) O \( <\) F

Hint:

Electronegativity increases across a period and decreases down a group. Remember to use the Pauling scale for accurate electronegativity comparisons.

Answer 1

The Correct Option is A

The correct order of electronegativity on the Pauling scale is: \[ \text{Li} = 1, \, \text{Be} = 1.5, \, \text{B} = 2, \, \text{C} = 2.5, \, \text{N} = 3, \, \text{O} = 3.5, \, \text{F} = 4.0 \] Thus, the correct order should be: \( \text{Mg} <\text{Al} <\text{B} <\text{N} \), and the incorrect order is \( \boxed{\text{(1)}} \).

Answer 2

Electronegativity generally increases from left to right across a period and decreases down a group in the periodic table.

Checking each option:

• Option (1): Al < Mg < B < N
  This is incorrect because Mg (group 2) is to the left of Al (group 13) in the same period. Therefore, Mg should be less electronegative than Al.
  The correct order is: Mg < Al < B < N.
• Option (2): Al < Si < C < N — ✔️ Correct (trend across the period).
• Option (3): Mg < Be < B < N — ✔️ Correct (trend across and down periods).
• Option (4): S < Cl < O < F — ✔️ Correct (F is most electronegative).

Final Answer:

✅ Option (1) — Al < Mg < B < N is incorrect.