Question

Number of compounds from the following with zero dipole moment is _______.
HF, H$_2$, H$_2$S, CO$_2$, NH$_3$, BF$_3$, CH$_4$, CHCl$_3$, SiF$_4$, H$_2$O, BeF$_2$

Answer 1

A molecule has a zero dipole moment if it is symmetric, and the bond dipoles cancel each other out. Let us analyze each compound:
$\text{H}_2$: Diatomic, nonpolar, symmetric. - Dipole moment = 0.
$\text{CO}_2$: Linear molecule, symmetric. - Dipole moment = 0.
$\text{BF}_3$: Planar triangular structure, symmetric. - Dipole moment = 0.
$\text{CH}_4$: Tetrahedral geometry, symmetric. - Dipole moment = 0.
$\text{SiF}_4$: Tetrahedral geometry, symmetric. - Dipole moment = 0.
$\text{BeF}_2$: Linear molecule, symmetric. - Dipole moment = 0.
Molecules with nonzero dipole moments:
$\text{HF}$: Polar molecule, asymmetric.
$\text{H}_2\text{S}$: Bent structure, asymmetric.
$\text{NH}_3$: Trigonal pyramidal structure, asymmetric.
$\text{CHCl}_3$: Tetrahedral, but asymmetric due to $\text{Cl}$.
$\text{H}_2\text{O}$: Bent structure, asymmetric.
Conclusion: The compounds with zero dipole moment are:
$\text{H}_2, \, \text{CO}_2, \, \text{BF}_3, \, \text{CH}_4, \, \text{SiF}_4, \, \text{BeF}_2.$
The number of such compounds is:
$6.$
Final Answer: 6.