In the following set of elements, one element does not belong to the set. Select this element and explain why it does not belong:
`""_(13)^(27)A,""_(12)^(24)B, ""_(11)^(23)C,""_(10)^(22)D`

Explanation

The lower figures in the above symbols indicate the atomic numbers of the respective elements. Thus, the atomic number of element `A=13, B=12,C=11` and `D=12`. Now let us write doen the electronic configurations of these elements by using these atomic numbers. These are given below:

(i) Element `A, B` and `C` contain three electron shells each so tal of the them belong to the same period (3rd period). The elemen `D` has two electron shells, so it belong to a different period (2nd period) of the periodic table. Thus, being in a different period element `D` does not belong to the set.
(ii) If we look at the above electronic configurations, we find the elements `A,B` and `C` have 3,2 and 8 valence electrons and hence it is an inert gas which is a non-metal. Thus, being a non metal, element `D` does not belong to the set.