d- and f-Block Elements
- The electronic configurations of Eu (Atomic No. 63), Gd (Atomic No. 64) and Tb (Atomic No. 65) are : Answer: 4. [Xe]4f⁷6s² , [Xe]4f⁷5d¹6s² and [Xe]4f⁹6s² Key idea: half-filled 4f⁷ is extra stable, and Gd and Tb follow from it. Eu (63): [Xe]4... 1
- Match items of Column I with the items of Column II and assign the correct code :Column I: (a) Cyanide process; (b) Froth floatation process; (c) Electrolytic reduction; (d) Zone refiningColumn II: (i) Ultrapure Ge; (ii) Dressing of ZnS; (iii) Extrac… Answer: 1. (iv) (ii) (iii) (i) Key idea: match each process with its use. (a) Cyanide process: extraction of gold (Au), iv. (b) Froth floata... 1