Question

The dipole moment value of which of the following molecules is maximum?

• A. BeF\(_2\)
• B. H\(_2\)O
• C. NH\(_3\)
• D. CH\(_4\)

Hint:

The dipole moment depends on both bond polarity and molecular geometry. Symmetrical molecules such as \(CH_4\) and \(BeF_2\) have zero net dipole moment because individual bond moments cancel out.

Answer 1

The Correct Option is B

Step 1: Recall dipole moment definition.
Dipole moment \(\mu = q \cdot r\), depends on magnitude of charge separation and geometry.

Step 2: Molecular geometry effect.
H\(_2\)O → bent geometry → vector sum of bond dipoles nonzero → high dipole moment.

Step 3: Symmetry check.
BeF\(_2\) → linear → bond dipoles cancel → net \(\mu = 0\).

Step 4: NH\(_3\).
Trigonal pyramidal → dipole moment exists, but smaller than H\(_2\)O.

Step 5: CH\(_4\).
Tetrahedral symmetry → bond dipoles cancel → \(\mu = 0\).

Step 6: Conclusion.
Hence, H\(_2\)O has maximum dipole moment among these molecules.