Question

A diabetic person’s exhaled breath contains propanone. A student tries to test the diabetes by asking the guy to bubble the reagent with his exhaled breath. Which of the following reagent could give positive result 1. Aqueous Bromine 2. Fehlings reagent 3. Tollens’ reagent 4. Alkaline aqueous iodine​

Answer 1

Answer:

2 is the answer to this question

Answer 2

Alkaline aqueous iodine(4) will give a positive result

Explanation:

• The reaction is referred to as Iodoform reaction. A yellow precipitate is formed when an alkaline aqueous solution of iodine reacts with a ketone ( that contains a methyl group) . It also results in a peculiar antiseptic smell.
• The reaction of iodine with ketone occurs in the following manner:

      $I_2 + ketone \rightarrow iodoketone + I^- + H^+$

• The pale yellow precipitate of iodoform that is formed, is indicative of a positive iodoform test.
• Hence the diabetic patient's exhaled breath (containing propanone) will give a positive result with Aqueous iodine in the presence of a base.