Electronegativity is the tendency of an atom to attract a shared pair of electrons towards itself. For carbon atoms, electronegativity is influenced by the hybridization state.

Concept: The electronegativity of a carbon atom increases with increasing s-character in its hybrid orbitals. This is because s-orbitals are closer to the nucleus than p-orbitals, so electrons in s-orbitals are held more tightly. A higher s-character means the hybrid orbital has more s-orbital character, bringing the shared electrons closer to the nucleus and thus increasing electronegativity.

• sp-hybridised carbon: Has 50% s-character (one s and one p orbital).
• sp²-hybridised carbon: Has 33.3% s-character (one s and two p orbitals).
• sp³-hybridised carbon: Has 25% s-character (one s and three p orbitals).

Since sp-hybridised carbon has the highest s-character (50%), it is the most electronegative among the three hybridization states.

Option Analysis:

• A) sp³ hybridised carbon atom: Has 25% s-character, making it the least electronegative among the options.
• B) sp-hybridised carbon atom: Has 50% s-character, making it the most electronegative. This is the correct answer.
• C) sp² hybridised carbon atom: Has 33.3% s-character, which is intermediate between sp and sp³.
• D) Always same irrespective of its hybrid state: This is incorrect, as electronegativity varies significantly with hybridization due to changes in s-character.

Correct Answer: (B)