Question

potassium and caesium rather than lithium are used in photoelectric effect​

Answer 1

Potassium and caesium are used in photoelectric cells rather than lithiumbecause potassium and caesium have much lower ionisation enthalpy thanthat of lithium. As a result, these two metals when subjected to light, emit electrons but lithium does not

Answer 2

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Smaller in size and therefore, requires high energy to lose an electron. Pottasium and caesium have much lower ionization enthalpy than that of lithium as a result, these metals exposure to light, easily emit electrons but lithium doesn`t therefore potassium and cesium rather than lithium used in photoelectric effect.