Question

the atomic number of three elements A B and C are 12 18 20.state given reason, which two elements will show similar properties?

Answer 1

A and C have similar characters because they are in same group of classification

Answer 2

 A = Atomic number = 12  ,   Electronic configuration = 2,8,2
 B = Atomic number = 18,     Electronic configuration = 2,8,8
 C =  Atomic number = 20 ,   Electronic configuration = 2,8,8,2

Element A and C will be similar.
This is because:
1) They have same number of valence electrons
2) both of them have the same valency of (+2)

Therefore they will be similar.

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