Question

Among the following, the number of metal/s which can be used as electrodes in the photoelectric cell is _____ (integer answer).

• A. $\mathrm{Li}$
• B. $\mathrm{Na}$
• C. $\mathrm{Rb}$
• D. $\mathrm{Cs}$

Answer 1

The correct option is D

$\mathrm{Cs}$

Explanation for correct option:

(D) $\mathbf{Cs}$

1. Cesium is used as an electrode in photoelectric cells because its ionization potential is low.
2. Due to which its valence shell electrons can be easily ejected out by the energy of light..

Explanation for incorrect option:

(A) $\mathbf{Li}$

1. Lithium cannot be used as an electrode in photoelectric cells because its ionization potential is high.
2. As it has a smaller size.

(B) $\mathbf{Na}$

1. Sodium cannot be used as an electrode in photoelectric cells because its ionization potential is high.
2. As it has a smaller size.

(C) $\mathbf{Rb}$

1. Rubidium cannot be used as an electrode in photoelectric cells because its ionization potential is higher than that of cesium.
2. As it has a smaller size than cesium.

Hence, option D is correct, $\mathrm{Cs}$ is used as an electrode in photoelectric cells,