(i) The correct order of ionic radii is shown below.
Pr3+
>
Sm3+
>
Dy3+
1.013Å
0.964Å
0.908Å
(ii) Eu2+ acts as strong reducing agent as +2 oxidation state oxidizes to +3 easily. (iii) Pu shows +7 oxidation state. It can use maximum eightelectrons because its electronic configuration is 5f66d07s2 Therefore, (ii) and (iii) statements are correct.