Question

*Most chemically reactive metal*. Though it is quite rare, it is used in some *photoelectric cells* and *atomic clocks*.

Answer 1

Cesium is the most chemically reactive metal, which reacts explosively with water and ignites spontaneously in air. It is used in some photoelectric cells and atomic clocks.

Step-by-step explanation:

The most chemically reactive metal is cesium. Although it is quite rare, cesium is used in some photoelectric cells and atomic clocks. Cesium reacts explosively with water and will ignite spontaneously in air.