If pairs of enantiomers are only counted once, how many different aldehydes have the molecular formula C₅H₁₀O? A) 2 B) 3 C) 4 D) 5

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The molecular formula C5H10O corresponds to aldehydes with five carbon atoms. When considering enantiomers as a single entity, we need to identify the structures that can have chiral centers. For aldehydes with this formula, the variability comes from the placement of the double bonded oxygen (which must be at the end for it to be an aldehyde) and the distribution of the remaining carbon atoms in the chain or forming branches. The possible structures include: a straight-chain aldehyde with no chiral centers, an aldehyde with a methyl branch at the second carbon (creating a potential chiral center), an aldehyde with a methyl branch at the third carbon (also creating a potential chiral center), and an aldehyde with ethyl branch at the second carbon (which does not create a chiral center because of symmetry). Considering enantiomers as one, we have four distinct structures: straight-chain, one with a methyl branch at the second carbon (two enantiomers counted as one), one with a methyl branch at the third carbon (two enantiomers counted as one), and one with an ethyl branch at the second carbon. This gives us a total of four different aldehydes.

If Pairs of Enantiomers Are Only Counted Once, How Many