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

Match items of Column I with the items of Column II and assign the correct code.
        Column l                                                                    Column II
A. Cyanide process                                                            1. Ultrapure Ge
B. Froth floatation process                                                 2. Dressing of ZnS
C. Electrolytic reduction                                                      3. Extraction of Al
D. Zone refining                                                                  4. Extraction of Au
                                                                                            5. Purification of Ni
Codes
      A  B  C  D
(a)  2  3  1  5
(b)  1  2  3  4
(c)  3  4  5  1
(d)  4  2  3  1

Aluminium is extracted from alumina (Al₂O₃) by electrolysis of a molten mixture of :

1. Al₂O₃ + HF + NaAlF₄

2. Al₂O₃ + CaF₂ + NaAlF₄

3. Al₂O₃ + Na₃AlF₆ + CaF₂

4. Al₂O₃ + KF +Na₃AlF₆

During extraction, copper is obtained by the reduction of cupric oxide with:

1. Cu₂S

2. SO₂

3. FeS

4. CO

A pair of metals among the following that can be purified by the van Arkel method are:

1. Zr,  and Ti

2. Ag, and Au

3. Ni,  and Fe

4. Ga, and In

Sulphide ores of metals are usually concentrated by Froth Flotation process. Which one of the following sulphide ores offers and exception and is concentrated by chemical leaching?

Percentage of silver in the alloy, German Silver is:-

1. 2.5%

2. 1.5%

3. 10%

4. 0%

Aluminium is used as a reducing agent in the reduction of :-

1. Cr₂O₃

2. SnO₂

3. ZnO

4. HgO

Which of the following has a negative slope?

1. C $\to$CO

2. Fe $\to$Fe₂O₃

3. Mg $\to$MgO

4. All of the above