Let’s compare the known electronegativities (Pauling scale) of the elements in each option:

F ~ 3.98

O ~ 3.44

N ~ 3.04

Cl ~ 3.16

C ~ 2.55

B ~ 2.04

S ~ 2.58 (sometimes listed as 2.5–2.58)

Si ~ 1.90

Al ~ 1.61

Be ~ 1.57

Mg ~ 1.31

Now, check each statement:

Option A: $\mathrm{S}<\mathrm{Cl}<\mathrm{O}<\mathrm{F}$

S (2.58) < Cl (3.16) < O (3.44) < F (3.98)

This order is correct.

Option B: $\mathrm{Al}<\mathrm{Si}<\mathrm{C}<\mathrm{N}$

Al (1.61) < Si (1.90) < C (2.55) < N (3.04)

This order is correct.

Option C: $\mathrm{Al}<\mathrm{Mg}<\mathrm{B}<\mathrm{N}$

Actual electronegativities are Al (1.61) and Mg (1.31).

The statement says “Al < Mg,” which would mean 1.61 < 1.31, which is wrong.

Therefore, Option C is incorrect.

Option D: $\mathrm{Mg}<\mathrm{Be}<\mathrm{B}<\mathrm{N}$

Mg (1.31) < Be (1.57) < B (2.04) < N (3.04)

This order is correct.

Answer: Option C is the incorrect order.