The short form of the modern periodic table of the elements (also called Bohr's table) is the most convenient and widely used version of the periodic table. It consists of_______horizontal rows called periods and________vertical columbs called groups.

Options

A. `7, 18`
B. `8, 16`
C. `6, 15`
D. `5, 13`

Answer

A

Explanation

There are altogether seven periods. These are numbered as `1, 2, …, 7` from top to bottom. There are `18` vertical columns. Elements having similar valence shell electronic configurations in their atoms are arranged under each other in vertical columns referred to as groups of families. These groups are numbered from `1` to `18`.