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Structure of Atom question

2021 · 25 Feb · Shift 2 · Q23
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Structure of Atom question

2021 · 25 Feb · Shift 2 · Q23

JEE MainChemistryStructure of AtomNumerical+4 / −1
Among the following, number of metal/s which can be used as electrodes in the photoelectric cell is ‾\underline{\hspace{2cm}}​. (Integer answer) (A) Li (B) Na (C) Rb (D) Cs
Numerical answer
View written solutionFree

Correct answer: 1

  1. Principle of photoelectric cell electrode material

    In a photoelectric cell, the metal used as the photosensitive electrode should have low ionization enthalpy / low work function so that electrons can be emitted easily when light falls on it.

    Alkali metals are commonly considered because they have very low work functions.

  2. Check the given metals

    The metals listed are:

    • (A) Li
    • (B) Na
    • (C) Rb
    • (D) Cs

    Among alkali metals, the work function decreases down the group, so photoelectric emission becomes easier for heavier alkali metals.

  3. Practical use in photoelectric cells

    In standard chemistry discussions, the metals commonly used as photoelectric cell electrodes are the highly electropositive alkali metals such as:

    • Cs
    • sometimes K and Rb are also mentioned

    But from the given list, cesium (Cs) is the standard metal specifically used because it has the lowest work function among these and is most suitable.

  4. Count the number of suitable metals

    From the given options, the metal used as electrode in a photoelectric cell is:

    • Cs

    Therefore, the number of such metals is:

    111

  5. Comparison with stored answer

    Derived answer = 111

    Stored correct answer = 111

    Hence, both agree.

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