Final answer:
The best method for preparing the given ketone from an appropriate alcohol in one step is to use sodium dichromate and sulfuric acid as the oxidizing agent.
Step-by-step explanation:
The best method for preparing the given ketone (CH₂CH=O, acetaldehyde) from an appropriate alcohol in one step is to use an oxidizing agent such as Na₂Cr₂O₇ (sodium dichromate) in the presence of H₂SO₄ (sulfuric acid).
The reaction would proceed as follows:
Starting alcohol: CH₂CH₂OH → Ketone: CH₂CH=O
Na₂Cr₂O₇ + H₂SO₄ → H₂Cr₂O₇ + Na₂SO₄
H₂Cr₂O₇ + CH₂CH₂OH → CH₂CH=O + Cr₂O₃ + H₂O