The difference in atomic numbers of the inert gas and alkali metal in the 5th period of the moden long form of periodic table is

Options

A. 17
B. 20
C. 12
D. 16

Answer

A

Explanation

In V period
Atomic no. of Alkali metral `= 37 (Rb)` and Atomic no. of xenon `= 54`
`:. "Diff"^(n) = 54 - 37 = 17`