Concept:A carbon atom is sp hybridized when it forms two sigma bonds and two pi bonds, typically seen in triple bonds or consecutive double bonds.
Solution:- Let's analyze the bonding of the carbon atom in each group:
- A: \( \text{-CHO} \) (Aldehyde) contains a \( \text{C}=\text{O} \) double bond \( \rightarrow \) sp².
- C, D: \( \text{-COOH} \) and \( \text{-COOR} \) contain a \( \text{C}=\text{O} \) double bond \( \rightarrow \) sp².
- B: \( \text{-CN} \) (Nitrile or Cyano group) consists of a carbon triply bonded to a nitrogen (\( \text{-C}\equiv\text{N} \)). The carbon forms one sigma bond with N, one sigma bond with the R-group, and two pi bonds with N.
- This linear geometry requires sp hybridization.
Why other options are incorrect:Aldehydes, carboxylic acids, and esters all contain a carbonyl carbon, which is sp² hybridized.
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