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