In a $\mathrm{carbonyl}$ group, how many lone pairs of electrons does the $O$ atom possess?

• A. $2$
• B. $3$
• C. $1$
• D. $0$

Answer: (A)

Verified step by step guidance

1. Identify the structure of a carbonyl group, which consists of a carbon atom double-bonded to an oxygen atom (C=O).
2. Recall that oxygen has 6 valence electrons in total.
3. In the carbonyl group, oxygen forms a double bond with carbon, using 2 pairs (4 electrons) for bonding.
4. Subtract the bonding electrons from oxygen's valence electrons: 6 valence electrons - 4 bonding electrons = 2 electrons left as lone pairs.
5. Since lone pairs consist of 2 electrons each, the oxygen atom in a carbonyl group has 1 lone pair of electrons.