Read the given passage and answer the questions number 1 to 5 that follow : The d-block of the periodic table contains the elements of the groups 3 - 12 and are known as transition elements. In general, the electronic configuration of these elements is (n - 1) d^(1-10)ns^(1-2). The d-orbitals of the penultimate energy level in their atoms receive electrons giving rise to the three rows of the transition metals i.e., 3d, 4d and 5d series. However, Zn Cd and Hg are not regarded as transition elements. Transition elements exhibit certain characteristic properties like variable oxidation states, complex formation, formation of coloured ions and alloys, catalytic activity, etc. Transition metals are hard (except Zn, Cd and Hg) and have a high melting point. Why is Cu^(2+) ion coloured while Zn^(2+) ion is colourless in aqueous solution ?

Read the given passage and answer the questions number 1 to 5 that fol

1.	Read the given passage and answer the questions number 1 to 5 that follow : The d-block of the periodic table contains the elements of the groups 3 - 12 and are known as transition elements. In general, the electronic configuration of these elements is (n - 1) d^(1-10)ns^(1-2). The d-orbitals of the penultimate energy level in their atoms receive electrons giving rise to the three rows of the transition metals i.e., 3d, 4d and 5d series. However, Zn Cd and Hg are not regarded as transition elements. Transition elements exhibit certain characteristic properties like variable oxidation states, complex formation, formation of coloured ions and alloys, catalytic activity, etc. Transition metals are hard (except Zn, Cd and Hg) and have a high melting point. Why is Cu^(2+) ion coloured while Zn^(2+) ion is colourless in aqueous solution ?
Answer» Solution :In `Cu^(2+)`, there is EXCITATION of electrons from lower to higher d-orbitals. Some energy is ABSORBED and it shows COLOUR. In `Zn^(2+)`, there is no such POSSIBILITY.