Chapter 20

In the electrolysis of alumina, cryolite is added to : (a) lower the melting point of alumina (b) increase the electrical conductivity (c) minimise the anode effect (d) remove imnurities from alumina

Match the anionic species given in Column-I that are present in the ore(s) given in Column-II. [Adv. 2015] Column-I Column-II (A) Carbonate (p) Siderite (B) Sulphide (q) Malachite (C) Hydroxide (r) Bauxite (D) Oxide (s) Calamine (t) Argentite

Match the conversions in Column I with the type(s) of reaction(s) given in Column II. \([2008-6 M]\) Column I \(\quad\) Column II (A) \(\mathrm{PbS} \rightarrow \mathrm{PbO}\) (p) roasting (B) \(\mathrm{CaCO}_{3} \rightarrow \mathrm{CaO}\) (q) calcination (C) \(\mathrm{ZnS} \rightarrow \mathrm{Zn}\) (r) carbon reduction (D) \(\mathrm{Cu}_{2} \mathrm{~S} \rightarrow \mathrm{Cu}\) (s) self reduction

Match the extraction processes listed in Column I with metals listed in Column II : $$ [2006-6 M] $$ Column I \(\quad\) Column II (A) Self reduction (p) Lead (B) Carbon reduction (q) Silver (C) Complex formation and (r) Copper displacement by metal (D) Decomposition of iodide (s) Boron

Match the following choosing one item from column \(\mathbf{X}\) and the appropriate item from column \(\mathbf{Y}\) : [Multiple concept, \(1986-1 / 2 \times 8=4\) Marks] \(\mathbf{X}\) \(\mathbf{Y}\) (i) Lewis acid (a) \(\mathrm{K}\) electron capture (ii) Philosopher's wool (b) Zinc ore (iii) Electrophile (c) \(\mathrm{HCHO}\) (iv) Preservative (d) \(\mathrm{NH}_{4}^{+}\) (v) Electron emission (e) Small proton to neutron ratio (vi) \(\quad\) Bronsted acid (f) \(\mathrm{SO}_{3}\) (vii) Black jack (g) \(\mathrm{BF}_{3}\) (viii) \(\quad \mathrm{X}\)-ray emission (h) \(\mathrm{ZnO}\)

Partial roasting of chalcopyrite produces (a) \(\mathrm{Cu}_{2} \mathrm{~S}\) and \(\mathrm{FeO}\) (b) \(\mathrm{Cu}_{2} \mathrm{O}\) and \(\mathrm{FeO}\) (c) \(\mathrm{CuS}\) and \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) (d) \(\mathrm{Cu}_{2} \mathrm{O}\) and \(\mathrm{Fe}_{2} \mathrm{O}_{3}\)

State with balanced equations what happens when : (i) Write balanced equations for the extraction of copper from copper pyrites by self-reduction. [1990 - 2 Marks] (ii) Write balanced equations for the extraction of silver from silver glance by cyanide process.

Give the equations for the recovery of lead from Galena by air reduction.

What is the actual reducing agent of haematite in blast furnace?

Give reasons for the following : (i) Why is chalcocite roasted and not calcinated during recovery of copper?

Give balanced equations for extraction of silver from its sulphide ore

Give balanced equations for the extraction of aluminium from bauxite by electrolysis.

(a) Write the chemical equations involved in the extraction of lead from galena by self reduction process. (b) Match the following extraction processes with the appropriate metals listed below : (i) Silver (A) Fused salt electrolysis (ii) Calcium (B) Carbon reduction (iii) Zinc (C) Carbon monoxide reduction (iv) Iron (D) Amalgamation (v) Copper (E) Self reduction