The electronic configurations of three elements X, Y and Z are X — 2, 8; Y — 2, 8, 7 and Z — 2, 8, 2. Which of the following is correct?
(A) X is a metal
(B) Y is a metal
(C) Z is a non-metal
(D) Y is a non-metal and Z is a metal
The electronic configuration of X is 2,8. Since the outermost shell is completely full , it is a noble gas configuration.
The electronic configuration of Y is 2,8,7. In order to attain noble gas configuration, it needs to gain 1 electron . So, it is a nonmetal .
The electronic configuration of Z is 2,8,2. In order to attain noble gas configuration, it needs to lose 2 electrons . So, it is a metal
So, the correct answer is (d)