Assign the position of the element having outer electronic configuration: (i) ns²np⁴ for n=3, (ii) (n-1)d²ns² for n=4, and (iii) (n-2)f⁷(n-1)d¹ns² for n=6 in the periodic table.

(i) For n=3, the period in which the element belongs is third. The electronic configuration is 3s²3p⁴ and the element belongs to p block. The group number of the element is 10 + number of electrons in the valence shell = 10 + 6 = 16. Thus, the element belongs to third period and sixteenth group.
(ii) For n=4, the period in which the element belongs is fourth. The electronic configuration is 3d²4s² and the element belongs to d block. The group number of the element is = number of electrons in the (n-1)d subshell + number of electrons in ns subshell = 2 + 2 = 4. Thus, the element belongs to fourth period and fourth group.
(iii) For n=6, the period in which the element belongs is sixth. The electronic configuration is 4f⁷5d¹6s² and the element belongs to f block. All f block elements belong to third group. Thus, the element belongs to sixth period and third group.