Question

Read the assertion and reason carefully and answer the question on the basis of the following options. You have to select the one that best describes the two statements.

Assertion: Potassium and caesium are used in photoelectric cells.
Reason: Potassium and caesium emit electrons on exposure to light.

• A. If both assertion and reason are true and the reason is a correct explanation of the assertion
• B. If both assertion and reason are true but reason is not a correct explanation of the assertion
• C. If the assertion is true but reason is false
• D. If both the assertion and reason are false
• E. If the assertion is false but the reason is true

Answer 1

The correct option is A If both assertion and reason are true and the reason is a correct explanation of the assertion

Potassium and Caesium are electropositive elements with very low ionisation potential so they emit electrons on exposure to light.

Hence assertion is correct and the reason is the true explanation for the assertion.