A dimensionless quantity may have unit.
Two physical quantities having same dimensions, may have different units.

• If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
• If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2).
• If Assertion is true statement but Reason is false, then mark (3).
• If both Assertion and Reason are false statements, then mark (4).

To analyze the given statements about dimensionless quantities and physical quantities, let's break them down.

Assertion

A dimensionless quantity may have units. This statement is true because dimensionless quantities can be expressed in terms of ratios or comparisons, which may involve units.

Reason

Two physical quantities having the same dimensions may have different units. This statement is also true, as different measurement systems (like metric and imperial) can represent the same physical quantity with different units.

Relationship Between Assertion and Reason

While both statements are true, the reason does not directly explain the assertion. The assertion discusses dimensionless quantities, while the reason addresses the relationship between physical quantities and their units.

Final Evaluation

Based on the analysis:

• Assertion is true.
• Reason is true but does not explain the assertion.

The correct answer is (2).