Question:
The metal mainly used in devising photoelectric cells is :
(1) $\mathrm{Na}$
(2) Li
(3) $\mathrm{Rb}$
(4) $\mathrm{Cs}$
Correct Option: , 4
Solution:
Cesium has lowest ionisation enthalpy and hence it shows photoelectric effect to the maximum extent. So, it is used in photo electric cell.