The arrangemen t of orbitals on the basis of energy is based upon th eir (n + l) value. Lower the value o f (n + l), low er is th e energy. For o rb itals h aving sam e values of (n + l), th e o rb ital w ith low er value of n will have lower energy. (I) Based upon the above inform ation, arrange th e fo llo w in g o r b ita ls in th e in c re a s in g order of energy. (a) Is, 2s, 3s, 2p (b) 4s, 3s, 3p, 4d (c) 5p, 4d, 5d, 4f, 6s (d) 5f, 6d, 7s, 7p (II) Based u p o n th e above inform ation, solve the questions given below : (a) W hich of th e following orbitals has the lowest energy ? 4d, 4f, 5s, 5p (b) W hich of the following orbitals has the highest energy ? 5p, 5d, 5f, 6s, 6p

Explanation

(I) (a) `Is lt 2s lt 2p lt 3s (b) 3s lt 3p lt 4s lt 4d (c) 4dlt 5p lt 6s lt 4f lt 5d (d) 7s lt 5f lt 6d lt 7p`
(II) (a) 5s (b) 5f