xix) The element A,B,C,D and E have atomic
number 9, 11, 17, 12 and 13 respec-
tively. 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
Answers
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Answer:
(C) A and C is the correct answer.
Explanation:
We'll write the electronic configurations of the 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
We know that in a group, elements have same valence electrons.
Since, A and C have same valence electron i.e 7
Therefore, A and C belongs to same group.
Hope it helps :)
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