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Assertion : Potassium and caesium are used in photoelectric cells.

Reason : Potassium and caesium emit electrons on exposure to light.

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not correct explanation of A

(c) A is true but R is false

(d) A and R are false

 

1 Answer

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Best answer

Correct option (a) Both A and R are true and R is the correct explanation of A

Explanation:

The valence shell electron in the alkali metals is so loosely held that even the low energy photons (light) can eject this electron from the metal surface. This phenomenon is called photoelectric effect. K and Cs are used in photoelectric cells which arc sensitive to blue light.

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