Which of the following atoms has the lowest ionization potential ?

Options

A. `._(8)^(16)O`
B. `._(7)^(14)N`
C. `._(55)^(133)Cs`
D. `._(18)^(40)Ar`

Answer

C

Explanation

Since the `._(55)^(133) Cs` has larger size among the four atoms gives, thus the electrons present in the outermost orbit will be away from the nucleus and the electronstaitc force experienced by electrons due to nucleus will be minimum. Therefore the enegry required to librate electron from outher will be minimum in the case of `._(55)^(133) Cs`.