Question

The elements A, B, C, D and E have atomic

numbers 9, 11, 17, 12 and 13 respectively. The pair

of elements which belongs to the same group of

the periodic table is

a. A and B c. A and C

b.B and D d. D and E​

Answer 1

Answer:

c. A and C

Explanation:

Firstly, we will write the electronic configuration of all elements.

A (atomic no. 9) = 2,7

B (atomic no. 11) = 2,8,1

C (atomic no. 17) = 2,8,7

D (atomic no. 12) = 2,8,2

E (atomic no. 13) = 2,8,3

The elements with the same no. of electrons in their outermost shell will belong to the same group.

And from above we can observe that Element A and C have same valence electrons, so they belong to the same group.

Hope it helps..!!☺

Answer 2

Answer:

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