Question

Which of the following set of molecules are having zero dipole moment?

• A. HI, CO$_2$ and CCl$_4$
• B. H$_2$, CO$_2$ and BF$_3$
• C. NH$_3$, CO$_2$ and CCl$_4$
• D. HI, CH$_4$ and CCl$_4$
• E. HI, HCl and CCl$_4$

Hint:

Chemistry Tip: Symmetrical shape often cancels bond dipoles completely.

Answer 1

The Correct Option is B

Concept:
Dipole moment becomes zero when bond dipoles cancel due to symmetry.
Step 1: Check molecules with zero dipole moment.
- H$_2$: identical atoms, nonpolar $\Rightarrow \mu=0$ - CO$_2$: linear and symmetrical, dipoles cancel - BF$_3$: trigonal planar and symmetrical, dipoles cancel
Step 2: Check polar molecules in other options.
HI and HCl are polar diatomic molecules.
NH$_3$ is pyramidal and polar. So any option containing these cannot be fully zero dipole set.
Step 3: Final answer.
Only set with all zero dipole molecules is: $$\text{H}_2,\ \text{CO}_2,\ \text{BF}_3$$ Hence correct option is (B). :contentReference[oaicite:1]{index=1}