Question

Consider the following statements.

S1 : Fluorine does not form any polyhalide because it does not have d-orbitals in valence shell.

S2 : In ClF3 , the three lone pairs of electrons occupy the equatorial position.

S3 : In B2 and N2 molecules mixing of s- and p- atomic orbitals takes place.

Of these statements :

• A. S1 , S2 and S3 are correct
• B. S1 and S2 are correct
• C. S1 and S3 are correct
• D. S2 and S3 are correct

Answer 1

Answer: (C)

S1 and S3 are correct

Answer 2

S1 : as it does not have d–orbitalsS2 : ClF3

S3 : In B2 mixing of the $\sigma$g(2s) orbital with the $\sigma$g(2p) orbital lowers the energy of the $\sigma$g(2s) orbital and increases the energy of the $\sigma$g(2p) orbital to a higher level than the $\pi$ orbitals. As a result, the last two electrons are unpaired in the degenerate (having the same energy) $\pi$ orbitals, and the molecule is paramagnetic.

In N2 the $\sigma$g(2s) and $\sigma$g(2p) levels of N2 interact (mix) less than the B2 and C2 levels, and the $\sigma$g (2p) and $\pi$u(2p) are very close in energy.