Question

In which of the following $p \pi$ - $d \pi$ bonding is possible?

• A. $CO _{3}^{2-}$
• B. $PO _{4}^{3-}$
• C. $NO _{3}^{-}$
• D. $NO _{2}^{-}$

Answer 1

Answer: (B)

$PO _{4}^{3-}$

Answer 2

Carbon, oxygen and nitrogen atoms do not have any $d$ orbital available. Therefore, in $CO _{3}{ }^{2-}, NO _{2}^{-}$ and $NO _{3}$, there is no possibility of $p \pi- d \pi$ type of bonding. In $PO _{4}{ }^{3-}$ phosphorus atom has vacant $d$ orbital available which is used to form $p \pi- d \pi$ type of bonding with $p$ orbital of oxygen atom.