Which of the following is an incorrect match?

1. Kaolinite - Al₂(OH)₄Si₂O₅

2. Cuprite - Cu₂O

3. Siderite - FeCO₃

4. Calamine - ZnSO₄

Among the following a non-oxide ore is:

1. Malachite

2. Cuprite

3. Zincite

4. Bauxite

Among the following an iron mineral is:

1. Malachite

2. Cassiterite

3. Pyrolusite

4. Magnetite

Which are the most abundant elements present inside the earth's crust?

1. Al, and Fe 

2. Al, and Cu

3. Fe, and Cu

4. Cu, and Ag

Match the items in Column I with the items in Column II and assign the correct code.

Codes

The fundamental principle of froth flotation process is:

NaCN is a depressant that is used: 

The common impurities present in bauxite are:

a. $\mathrm{CuO}$                    

b. $\mathrm{ZnO}$                

c. ${\mathrm{Fe}}_2{\mathrm{O}}_3$                

d. ${\mathrm{SiO}}_2$

Choose the correct option:
1. a and b
2. b and c
3. c and d
4. a and d

The extraction of gold and silver involves leaching with CN^- ion. Silver is later recovered by:

1. Liquation

2. Distillation

3. Zone refining

4. Displacement with Zn