Question

N,C,O,B,Al which is the most electronegative element among these

Answer 1

Electronegative elements are thise which are capable of getting electrons easily.

Generally, Non-Metals are more electronegative and metals are more electropositive.

Electronegativity increases left to right (across) the period and decreases down the group.

Atomic Number of Boron (B) - 5 . (P-2 , G-13)
Atomic Number of Carbon (C) - 6 . (P-2 , G-14)
Atomic Number of Nitrogen (N) - 7 . (P-2 , G-15)
Atomic Number of Oxygen (O) - 8 . (P-2 , G-16)
Atomic Number of Aluminium (Al) - 9 . (P-3 , G-13)

here P stands for 'Period' and G stand for 'Group'

So most electonegative element is Oxygen.

Answer 2

Among N(Nitrogen), C(Carbon), O(Oxygen), B(boron), Al(Aluminium), Oxygen is the most electronegative element.

• The electronegativity decreases as we move down a group.
• Electronegativity increases moving across a period from left to the right.
• Nitrogen is in $15^{th}$ group and $2^{nd}$ period.
• Carbon is in $14^{th}$ group and $2^{nd}$ period.
• Oxygen is in the $16^{th}$ group and $2^{nd}$ period.
• Boron is in $13^{th}$ group and $2^{nd}$ period.
• Aluminum is in $13^{th}$ group and $3^{rd}$ period.
• Among $2^{nd}$ period elements, Oxygen is in the rightmost part of the periodic table.

So, Oxygen is the most electronegative.