Answer:
c. SP2
Explanation:
The image in the diagram below shows the structure of NO₃⁻
Nitrogen is the central atom with the electronic configuration of 1s² 2s² 2p³.
So in its outermost shell, it has 3 electrons and the hybridization is sp²
However,
According to Hund's rule:
The ground state of Nitrogen is;
1s² 2s² 2p³
↑↓ ↑ ↑ ↑ ↑
At the excited state when it is attached to 3 different oxygen ions, we have:
1s² 2s² 2p⁵
O⁻ ---> ↑↓ ↑↓ ↑↓ ↑↓ ↑
1s² 2s² 2p⁵
O⁻ ---> ↑↓ ↑↓ ↑↓ ↑↓ ↑
1s² 2s² 2p⁴
O⁻ ---> ↑↓ ↑↓ ↑↓ ↑ ↑
Thus, the 3 sp² orbital lies in a plane and form 3 N - O σ- bond and one π- bond.
