Question

Assertion (A) : Glucose gets oxidized to six carbon gluconic acid on reaction with bromine water.
Reason (R) : The carbonyl group is absent in the open chain structure of glucose.

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Assertion (A) is false, but Reason (R) is true.

Hint:

To distinguish between an aldehyde and a ketone, bromine water is used. It will oxidize Glucose (aldehyde) to Gluconic acid, but it will not react with Fructose (ketone).

Answer 1

The Correct Option is C

Step 1: Checking the assertion first.
Bromine water is a gentle oxidising agent, just strong enough to turn the aldehyde end of glucose, $-CHO$, into a carboxylic acid, $-COOH$, without touching the hydroxyl groups elsewhere on the molecule. The six-carbon acid that results is exactly gluconic acid, so the assertion describing this oxidation is factually correct.
Step 2: Checking the reason next.
The reason claims the open-chain form of glucose has no carbonyl group at all, but that is the opposite of the truth, the open-chain structure is built around a free aldehyde carbonyl at C-1. This same carbonyl is exactly what lets glucose form an oxime with hydroxylamine and a cyanohydrin with HCN, and it is also the very group bromine water oxidises in the assertion. So the reason is false.
Step 3: Matching to the answer codes.
A true statement paired with a false one, where the false one cannot possibly explain the true one, points to the assertion being true while the reason is false. \[ \boxed{\text{Assertion true, Reason false}} \]