Question

Given below are two statements:
Assertion (A): In a hand specimen quartz can be easily distinguished from orthoclase.
Reason (R): Orthoclase has lower refractive index than quartz.

• A. Both A and R are correct and R is the correct explanation of A
• B. Both A and R are correct but R is not the correct explanation of A
• C. A is correct but R is not correct
• D. A is not correct but R is correct

Hint:

Quartz lacks cleavage and shows conchoidal fracture, while orthoclase shows cleavage.

Answer 1

The Correct Option is B

Concept:
Quartz and orthoclase can be distinguished in hand specimen using physical properties.

Step 1: Check Assertion.
Quartz commonly shows conchoidal fracture and lacks cleavage, while orthoclase has two good cleavages. \[ A \text{ is correct} \]

Step 2: Check Reason.
Orthoclase has slightly lower refractive index than quartz. \[ R \text{ is correct} \]

Step 3: Check explanation.
Refractive index is not the main hand-specimen basis for distinguishing quartz from orthoclase. Cleavage and fracture are more useful in hand specimen. \[ R \text{ is not the correct explanation of } A \] \[ \therefore \text{Correct Answer is (B)} \]