pBlock ElementsII - Result Question 1
####1. The correct statement among the following is
(2019 Main, 12 April I)
(a) $\left(SiH _3\right) _3 N$ is planar and less basic than $\left(CH _3\right) _3 N$.
(b) $\left(SiH _3\right) _3 N$ is pyramidal and more basic than $\left(CH _3\right) _3 N$.
(c) $\left(SiH _3\right) _3 N$ is pyramidal and less basic than $\left(CH _3\right) _3 N$.
(d) $\left(SiH _3\right) _3 N$ is planar and more basic than $\left(CH _3\right) _3 N$.
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Solution:
- The correct statement is that $\left(SiH _3\right) _3 N$ is planar and less basic than $\left(CH _3\right) _3 N$. The compounds trimethylamine $\left(CH _3\right) _3 N$ and trisilylamine $\left(SiH _3\right) _3 N$ have similar formulae, but have totally different structures. In trimethylamine the arrangement of electrons is as follows :
In trisilylamine, three $s p^{2}$ orbitals are used for $\sigma$-bonding, giving a plane triangular structure.
