Question

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

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.