Explanation

(b)
Carbanion [image:12_image384.emf]
Here, the carbon atom carries a negative charge with lone pair of electrons and has eight electrons in outermost orbit and complete its octet.
[image:12_image385.emf]Reactions in which carbanions are formed as intermediate are said to proceed by a “Carbanion mechanism”.
Carbanion is $sp^{3}$ hybridised, three $sp^{3}$ hybrid orbitals form covalent bonds with three atoms while the fourth $sp^{3}$ hybrid orbital has a non-bonding pair of electrons. It is pyramidal in shape as similar to $NH_{3}$.