In a ketone, how many hydrogen atoms is the $C_{=O}$ (carbonyl carbon) directly bonded to?

• A. $3$
• B. $0$
• C. $1$
• D. $2$

Answer: (B)

Verified step by step guidance

1. Identify the structure of a ketone functional group, which contains a carbonyl carbon (C=O) bonded to two other carbon atoms.
2. Recall that the carbonyl carbon is double bonded to an oxygen atom and single bonded to two other carbons, meaning it forms three bonds in total.
3. Understand that hydrogen atoms can only be directly bonded to carbon atoms if there are available valences after accounting for other bonds.
4. Since the carbonyl carbon in a ketone is bonded to one oxygen (double bond) and two carbons (single bonds), it has no remaining valences to bond with hydrogen atoms.
5. Therefore, conclude that the carbonyl carbon in a ketone is directly bonded to zero hydrogen atoms.