Chemistry Aldehydes & Ketones PMC 2021
PMDC Verified Question 46 of 94
How many carbon attached to carbonyl carbon in ketone?
A
2
B
3
C
4
D
1
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: 2
Concept:

The functional classification of carbonyl compounds is based on what atoms are directly attached to the carbonyl carbon (\( C=O \)).

Solution:

  • By definition, a ketone has the general formula \( R-CO-R' \).


  • The carbonyl carbon must be situated between two other carbon chains (alkyl or aryl groups).


  • Therefore, exactly 2 carbon atoms are directly bonded to the carbonyl carbon in any ketone.


Why other options are incorrect:

If only 1 carbon is attached (and the other bond goes to hydrogen), it is an aldehyde. If 0 carbons are attached, it is formaldehyde. A carbon atom cannot form more than 4 bonds, and since 2 bonds go to oxygen, attaching 3 or 4 carbons is physically impossible.

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