Assertion : `(CH_(3))_(3)N` geometry is pyramidal but in case `(SiH_(3))_(3)N` it is planar.
Reason :The maximum covalency of Si is six but that of C is four.

Options

A. If both `(A)` and `(R )` are correct and `(R )` is the correct explanation of `(A)`
B. If both `(A)` and `(R )` are correct and `(R )` is the correct explanation of `(A)`
C. If `(A)` is correct but `(R )` is incorrect
D. If `(A)` is incorrect but `(R )` is correct

Answer

B

Explanation

Both `(A)` and `(R )` are correct but `(R )` is not the correct explanation of `(A)` Geometry of `(CH_(3))_(3)overset(..)N` is pyramidal due to non-availability of d-orbitals in `C` whereas geometry of `(SiH_(3))_(3)overset(..)H` is planar due to availility of d-orbitals in Si and it froms (p pi-d pi) back bonding .