Question

Identify the correct answer

• A. Three resonance structure can be drawn for ozone
• B. BF3 has non-zero dipole moment
• C. Dipole moment of NF3 is greater than that of NH3
• D. Three canonical forms can be drawn for $CO^{2-}_3$ion

Answer 1

Answer: (D)

Three canonical forms can be drawn for $CO^{2-}_3$ion

Answer 2

1. $BF_3$ is planar and symmetric, so it has zero dipole moment.

2. Dipole moment of $NH_3$ is greater than that of $NF_3$ due to opposite polarity.

3. $CO_3^{2-}$ ion has three equivalent resonance structures: $O=C-O^- \leftrightarrow O-C=O^- \leftrightarrow ^-C(O)O^-$

4. Ozone ($O_3$) has only two resonance structures.