The soft silvery metalic element which ionizes easily when heated or exposed to light and is present in atomic clocks is :

Options

A. Cerium
B. Cesium
C. Calcium
D. Californrium

Answer

B

Explanation

In 1967, based on Einstein defining the speed of light as the most constant dimension in the universem the Intrenational System of Units Isolated two specific wave counts from an emission spectrum of caesium-133 to co-define the second and the meter. Since then caesium has been widly used in highly accurate atomic clocks. Among alkali metals, cesium has lowest it can show photoelectric effect to the maximum extent.