The elements A, B, C, D and E have atomic number 9, 11, 17, 12 and 13 respectively

• GC Periodic Classification

The elements A, B, C, D and E have atomic number 9, 11, 17, 12 and 13 respectively. Which pair of elements belong to the same group?

1. A and B
2. B and D
3. A and C
4. D and E

Answer

Elements having the same number of valence electrons belong to the same group. Electronic configurations of the elements are:

A (9) - 2, 7

B (11) - 2, 8, 1

C (17) - 2, 8, 7

D (12) - 2, 8, 2

E (13) - 2, 8, 3

As, both A and C elements have the same number of valence electrons which is 7, hence they belong to the same group, i.e. 17^th group of the periodic table.

The correct option is C.