The atomic numbers of four elements A, B, C and D are 12, 13, 15 and 3 respectively. The element which cannot form a cation is :
(a) A
(b) B
(c) C
(d) D
Electronic configurations of the given elements are:
Element A - 2, 8, 2
Element B - 2, 8, 3
Element C - 2, 8, 5
Element D - 2, 1
Element C will not form a cation. It will form an anion as it will gain electrons.