Among the alkali metals cesium is the most reactive because

Options

A. its incomplete shell is nearest to the nucleus
B. it has a single electron in the valence shell
C. it is the heaviest alkali metal
D. the outermost electron is more loosely bound than the outermost electron of the other alkali metals.

Answer

D

Explanation

Alkali metals are highly reactive since they have a strong tendency to lose the single valence s-electron to form unipositive ions having inert gas configuration. In case of cesium, the distance of the valence electron is maximum (among the alkali metals) so force of attraction by the nucleus is least, hence it is most reactive.