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

Options

A. A and B
B. B and D
C. A and C
D. D and E

Answer

C

Explanation

Electronic configuration of A (atomic number 9) is 2,7
Electronic configuration of B (atomic number 11) is 2,8,1
Electronic configuration of C (atomic number 17) is 2,8,7
Electronic configuration of D (atomic number 12) is 2,8,2
Electronic configuration of E (atomic number 13) is 2,8,3
Elements which differ in atomic numer by 8 i.e., 9 (A fluorine) and 17 (Cl, chlorine) lie in the same group i.e., group 17 (halogens).