Question

Which of the following atoms has the lowest ionization potential?

• A. ${}_7^{14}N$
• B. ${}_{55}^{133}Cs$
• C. ${}_{18}^{40}Ar$
• D. ${}_8^{16}O$

Answer 1

Answer: (B)

${}_{55}^{133}Cs$

$\begin{array}{c}\text{The increase in the atomic number causes}\\ \text{an increase in the atomic radius.}\\ \text{and hence the ionization of the atom becomes}\\ \text{easy due to increase in atomic radius.}\\ \text{Hence}\text{Cs has lowest ionization potential.}\end{array}$