Which of the following reacts with aqueous alkaline iodine togive a yellow precipitate?
Correct answer: B. Ethanol
- A. 1-Propanol
- B. Ethanol
- C. Methanol
- D. 2-Methyl-2-propanol
Explanation
This describes the iodoform test. The test is positive for compounds containing a methyl ketone group (CH₃-CO-) or alcohols that can be oxidized to a methyl ketone (like ethanol and other secondary alcohols with the -OH on the second carbon). Ethanol is oxidized to acetaldehyde, which then reacts to give a yellow precipitate of iodoform (CHI₃).
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About Alcohols and Phenols
Alcohols are classified as primary, secondary or tertiary and studied through their hydrogen bonding, acidity, oxidation and reactions with active metals, acids and halogenating agents. Phenols require separate treatment because the hydroxyl group is attached to an aromatic ring, making their acidity and electrophilic substitution different from ordinary alcohols.
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535 free Alcohols and Phenols MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.
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