Question

Consider the following molecules.

I. BF₃
II. CHBr₃ (C is the central atom.)
III. Br₂
IV. XeCl₂
V. CO
VI. SF₄
Select the molecule(s) that fit the given statement.

These molecules have a zero net dipole moment.
A. I, III, IV
B. III, V
C. III, IV, V
D. none of them
E. I, III, IV, VI

Answer 1

The correct answer is option A. The molecules BF₃, Br₂, and XeCl₂ have a zero net dipole moment due to their symmetrical shapes, which allows for dipole moments to cancel out. SF₄ and CO do have a net dipole moment because of their asymmetrical shapes and uneven charge distribution.

Step-by-step explanation:

The question asks to select the molecule(s) that have a zero net dipole moment. A molecule with zero net dipole moment is nonpolar, meaning the charges are evenly distributed throughout the molecule, and any existing individual dipole moments (from polar bonds) cancel each other out.

BF₃ (Boron trifluoride) has a trigonal planar shape, which is highly symmetric, and because all B-F bonds are equal and symmetrically arranged around the central boron atom, the dipole moments cancel out, resulting in a molecule with zero net dipole moment.

Br₂ (Bromine molecule) is diatomic with two identical atoms sharing electrons equally, so there is no dipole moment.

XeCl₂ (Xenon dichloride) is linear with symmetrical electron distribution around Xe, resulting in no overall dipole moment.

SF₄ (Sulfur tetrafluoride) has a see-saw shape due to one pair of non-bonding electrons, which creates an asymmetrical shape, leading to a net dipole moment, so it's not nonpolar.

CO (Carbon monoxide) has polar bonds and fails to have a symmetrical distribution of charge, leading to a dipole.

Therefore, the molecules that have a zero net dipole moment are BF₃, Br₂, and XeCl₂. The correct answer is option A: I, III, IV.