Question

Which of the following pairs of atomic numbers represent elements belonging to the same group"

• A. 11, 20
• B. 12, 30
• C. 13, 31
• D. 14, 33

Answer 1

Answer: (C)

13, 31

Option A :

At. No.	EC
11	2, 8, 1
20	48, 8, 2

Option B :

At. No.	EC
12	2, 8, 3
30	2, 8, 18, 2

(but this belong to transition elements)

Option C :

At. No.	EC
13	2, 8, 3
31	2, 8, 18, 3

[They belong to same group III A]

Option D :

At. No.	EC
14	2, 8, 4
33	2, 8, 18, 5

Hence, the correct option is $\text{C}$