Question

Assertion (A) : D (+) – Glucose is dextrorotatory in nature. Reason (R) : (+) represents dextrorotatory nature and D represents the configuration.

• 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:

Never confuse D/L notation with (+)/(–) notation. D and L indicate configuration relative to glyceraldehyde. (+)/(–) indicate the direction of optical rotation. A D-compound may be either dextrorotatory or levorotatory depending on its actual optical behaviour.

Answer 1

The Correct Option is A

Step 1: Decode the two symbols in D(+)-glucose.
The symbol $D$ denotes relative configuration (spatial arrangement compared to D-glyceraldehyde). The symbol $(+)$ denotes optical rotation: the compound rotates plane-polarised light clockwise. These two properties are independent of each other.
Step 2: Verify the Assertion.
Since the name carries the $(+)$ sign, D(+)-glucose definitively rotates plane-polarised light in the dextro (clockwise) direction. The Assertion is true.
Step 3: Evaluate the Reason and its explanatory link.
The Reason correctly states that $(+)$ represents dextrorotatory nature while $D$ represents configuration. This is precisely the justification for the Assertion: the dextrorotatory property follows from the $(+)$ sign, not from $D$. Both statements are true and the Reason correctly explains the Assertion.
\[ \boxed{\text{Option (A)}} \]