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Question
Assertion :Li is used in photocells. Reason: Cs has lower ionization energy than Li.
Assertion :Li is used in photocells. Reason: Cs has lower ionization energy than Li.
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Solution
The correct option is D Assertion is incorrect but Reason is correct
The ionization enthalpies of the alkali metals are considerably low and decrease down the group fromLi to Cs. This is because the effect of increasing size outweighs the increasing nuclear charge,and the outermost electrons is very well screened fromthe nuclear charge.The alkali metals when irradiated with light, the light energy absorbed may be sufficient to make anatomlose electron. This property make caesium and potassium useful as electrodes in photoelectric cells.
The ionization enthalpies of the alkali metals are considerably low and decrease down the group fromLi to Cs. This is because the effect of increasing size outweighs the increasing nuclear charge,and the outermost electrons is very well screened fromthe nuclear charge.The alkali metals when irradiated with light, the light energy absorbed may be sufficient to make anatomlose electron. This property make caesium and potassium useful as electrodes in photoelectric cells.
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