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

Correct Answer: 6

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.

Answer 2

Step 1: Recall the condition for zero dipole moment.
A molecule has zero dipole moment when its individual bond dipoles cancel out due to symmetrical geometry or absence of polarity in bonds.

Step 2: Analyze each compound.
1. HF – Polar molecule (heteronuclear diatomic), μ ≠ 0
2. H₂ – Nonpolar (homonuclear diatomic), μ = 0 ✅
3. H₂S – Bent shape, dipoles do not cancel, μ ≠ 0
4. CO₂ – Linear, dipoles cancel out, μ = 0 ✅
5. NH₃ – Trigonal pyramidal, dipoles do not cancel, μ ≠ 0
6. BF₃ – Trigonal planar, symmetrical, μ = 0 ✅
7. CH₄ – Tetrahedral, symmetrical, μ = 0 ✅
8. CHCl₃ – Not symmetrical, μ ≠ 0
9. SiF₄ – Tetrahedral, symmetrical, μ = 0 ✅
10. H₂O – Bent shape, dipoles do not cancel, μ ≠ 0
11. BeF₂ – Linear, symmetrical, μ = 0 ✅

Step 3: Count the number of compounds with zero dipole moment.
Compounds with μ = 0 → H₂, CO₂, BF₃, CH₄, SiF₄, BeF₂

Step 4: Final Answer.
Number of compounds with zero dipole moment = 6

Final Answer: 6