Molecular symmetry determines overall dipole moment

Steps:

• Identify that all molecules are tetrahedral with C central atom and bonds to H/Cl.
• Note Cl is more electronegative than H/C, creating individual bond dipoles from C-Cl and C-H.
• Assess symmetry: overall dipole is zero if bond dipoles cancel due to identical surrounding atoms.
• Conclude CCl4 has full symmetry (four Cl), while others have uneven H/Cl distribution.

Why D is correct:

• CCl4's tetrahedral symmetry with four identical Cl atoms results in canceling bond dipoles, yielding zero net dipole per vector addition principle.

Why the others are wrong:

• A. CH3Cl: Asymmetric with one Cl, net dipole toward Cl.
• B. CH2Cl2: Two Cl atoms create unbalanced dipoles, net toward Cl side.
• C. CHCl3: Three Cl atoms pull electron density unevenly, net dipole toward Cls.

Final answer: D