Question

The atomic number of the element from the following with lowest \(1^{st}\) ionisation enthalpy is :

(1) 32

(2) 35

(3) 87

(4) 19

Answer 1

Correct option is: (3) 87

Atomic no. 32 \(\Rightarrow Ge\)

Atomic no. 35 \(\Rightarrow Br\)

Atomic no. 87 \(\Rightarrow Fr\)

Atomic no. 19 \(\Rightarrow K\)

Lowest first I.E. among the given element will be of \(Fr[87]\) .

\(Fr - [Rn] \ 7s^1\)