The number of unpaired electrons in a paramagnetic diatomic molecule of an element with atomic number 16 is :-

The number of unpaired electrons in a paramagnetic diatomic molecule of an element with atomic number 16 is :-
A 2
B 3
C 4
D 1

Detailed Solution

The element with atomic number 16 is sulphur. Its diatomic molecule is $S_2$.
Sulphur belongs to the same group as oxygen, so the molecular orbital configuration of $S_2$ in its valence shell is like that of $O_2$.
In $O_2$ the last two electrons enter the two degenerate antibonding orbitals $\pi^*2p_x$ and $\pi^*2p_y$ singly (Hund's rule).
Similarly, in $S_2$ the last two electrons occupy the two degenerate $\pi^*3p$ orbitals singly: $\pi^*3p_x^1 = \pi^*3p_y^1$.
So $S_2$ has two unpaired electrons according to molecular orbital theory, which makes it paramagnetic like $O_2$.
The number of unpaired electrons is 2.

Molecular Orbital Theory in past papers

19 questions from this chapter have appeared across 12 exam years.

Keep going

Practise Molecular Orbital Theory All 19 questions This chapter in 2006 AIPMT-PRE