Question

which hybridization is more electronegative

Answer 1

(That's why we say s orbital is said to be the most penetrating). Thus a hybrid orbital having more s-character will be more close to the nucleus and thus, more electronegative. This gives us the answer why sp carbon is more electronegative than sp2 and sp3 carbons.

Answer 2

SP as percentage of s character is 50% in it...which is the highest among all the hybridisstions.