Which of the following atoms has the lowest ionization potential ?

Options

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

Answer

B

Explanation

Ionization potential will be lowest for the atom in which the electrons are the farthest from the nucleus. So, the atom with the largest size will have the electron the farthest from the nuclei, hence to remove the electron from this atom will be easiest. so, the atom with least Ionization potential is `._(55)^(133)Cs`.