Question

Which one of the following molecules contains no $\pi$ bond ?

• A. $NO_2$
• B. $CO_2$
• C. $H_2 O$
• D. $SO_2$

Answer 1

Answer: (C)

$H_2 O$

Answer 2

All the molecules have O-atom with lone pairs, but in $H_2 O$ the H-atom has no vacant (in oxygen atom, absence of d-orbital) orbital for $\pi$-bonding.
That- why it does not have any $\pi$-bond.
In all other given molecules, the central atom because of the presence of vacant orbitals is capable to form $\pi$-bonds.