Question

Which of the following carbon atoms is most electronegative?
$\stackrel{III}{{CH}_3}-\stackrel{II}{{CH}_2}-C\equiv \stackrel{I}{CH}$

• A. I
• B. II
• C. III
• D. All are equal electronegative

Answer 1

The correct option is A I

$\stackrel{III}{\underset{{sp}^3}{{CH}_3}}-\stackrel{II}{\underset{{sp}^3}{{CH}_2}}-\underset{sp}{C}\equiv \stackrel{I}{\underset{sp}{CH}}$
Elecronegativity $\propto$ s-character.
In $sp$ hybrid orbitals, s character = 50%
and in ${sp}^3$ hybrid orbitals, s character = 33.3%

Thus, option I is the most electronegative.