Solution:
Solution
According to Aufbau's principle,
orbitals with lower n+l have lower energy so as valuse of n+l increases, its energy increases.
Also, if (n+l) is same, lower is n, lower is energy of orbit.
here,
(i)n=4,l=1 n+l=5
(ii)n=4,l=0 n+l=4
(iiii)n=3,l=2 n+l=5
(iv)n=3,l=1 n+l=4
so order is
(iv)<(ii)<(iii)<(i)
