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Statement-1: Potassium and caesium are u...

Statement-1: Potassium and caesium are used in photo-electric cells.
Statement-2: Potassium and caesium emit electrons on exposure to light above certain minimum frequency.

A

If both assertion and reason are true and the reason is the correct explanation of the assertion

B

If both assertion and reason are true but reason is nto the correct exaplation of the assertion

C

If assertion is true but reason is false

D

If the assertion and reason both are false

Text Solution

Verified by Experts

The correct Answer is:
A
K and Cs emit electrons on exposure of light due to low ionisation potential.
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Statement-1: Cesium is useful as electrodes in photoelectric cells. Statement-2: Light energy absorbed by cesium is sufficient to make an atom of cesium to lose an electron.

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ERRORLESS -S AND P BLOCK ELEMENTS-Ordinary thinking (Alkali metals)
  1. The colour of the precipitate produced by adding NaOH solution to HgCl...

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  2. On heating sodium metal in a current of dry ammonia, the compound form...

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  3. The alum used for purifying water is

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  4. Which of the following metal hydroxides does not dissolve in sodium hy...

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  5. Excess of Na^(+) ions in our system causes

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  6. Among the alkali metals caesium is the most reactive because

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  7. The characteristic not related to alkali metal is

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  8. When Kl is added to acidified solution fo sodium nitrite,

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  9. A sudden large jump between the values of second and third ionisation ...

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  10. Ferric alum has the composition (NH(4))(2)SO(4). Fe(2)(SO(4)).xH(2)O...

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  11. RbO(2) is a

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  12. Which one of the following is used as a disinfectant in water treatmen...

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  13. Which of the following statements is correct regarding alkali metals

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  14. As compared to lithium, sodium reacts quickly with water because

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  15. Correct order of increasing activity is

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  16. Salt cake is

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  17. Assertion : Lithium forms lithium oxide (LiO(2)) Reason : N(2) molec...

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  18. Statement-1: Potassium and caesium are used in photo-electric cells. ...

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  19. Assertion : K,Rb and Cs form superoxides. Reason : The stability of ...

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  20. Ionic mobility of which of the following alkali metal ions is lowest w...

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