General Principles of Isolation of Elements · Question 17

The following reactions take place in the blast furnace in the preparation of impure iron. Identify the reaction pertaining to the formation of the slag.

1. Fe2O3(s) + 3CO(g) 2Fe(l) + 3CO2(g)
2. CaCO3(s) CaO(s) + CO2(g)
3. CaO(s) + SiO2(s) CaSiO3(s)
4. 2C(s) + O2(g) 2CO(g)

Which of the following elements is present as the impurity to the maximum extent in pig iron?

1. Manganese
2. Carbon
3. Silicon
4. Phosphorus

Which of the following pairs of metals is purified by van Arkel method?

1. Ga and In
2. Zr and Ti
3. Ag and Au
4. Ni and Fe

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

1. Galena
2. Copper pyrite
3. Sphalerite
4. Argentite

Which of the following statements about the advantage of roasting of sulphide ore before reduction is not true?

1. The fG of the sulphide is greater than those for CS2 and H2S.
2. The fG is negative for roasting of sulphide ore to oxide.
3. Roasting of the sulphide to the oxide is thermodynamically feasible.
4. Carbon and hydrogen are suitable reducing agents for metal sulphides.

The mass of carbon anode consumed (giving only carbon dioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is (Atomic mass : Al = 27)

1. 270 kg
2. 540 kg
3. 90 kg
4. 180 kg

The method of zone refining of metals is based on the principle of

1. greater mobility of the pure metal than that of the impurity
2. higher melting point of the impurity than that of the pure metal
3. greater noble character of the solid metal than that of the impurity
4. greater solubility of the impurity in the molten state than in the solid