Which one is a malachite from the following?

1. CuCO₃.Cu(OH)₂

2. CuFeS₂

3. Cu(OH)₂

4. Fe₃O₄

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

1. Argentite

2. Galena

3. Copper pyrite

4. Sphalerite

Which of the following elements is present as an impurity to the maximum extent in the pig Iron?
1. Carbon
2. Silicon
3. Phosphorus
4. Manganese

An interstitial compound among the following is:

1. Invar

2. Steel

3. Bell metal

4. Bronze

Which one of the following is a mineral of iron?

1. Malachite

2. Cassiterite

3. Pyrolusite

4. Magnetite

Roasting of sulphides gives the gas X as a by-product. This is a colourless gas with a choking smell of burnt sulphur and causes great damage to respiratory organs as a result of acid rain. Its aqueous solution is acidic and  acts as an oxidizing agent and its acid has never been isolated. The gas X is:

1. SO₂

2. CO₂

3. SO₃

4. H₂S

"Metals are usually not found as nitrates in their ores". Out of the following two (I and II) reasons which is/are true for the above observation? 

Considering Ellingham diagram, which of the following metals can be used to reduce alumina?

1. Fe

2. Zn

3. Mg

4. Cu

The correct statement among the following is:  

\((i) Zr + 2I_2 \xrightarrow{870K} ZrI_4 \xrightarrow{2075K} Zr + 2I_2 \)
\((ii) Ni + 4CO \xrightarrow{330K} Ni(CO)_4 \xrightarrow{450K} \underset{(pure)}{Ni} + 4CO \)

The processes (ii) and (i) above, respectively, are  : 

1. Mond's process; Van Arkel process

2. Van Arkel process; Mond's process

3. Goldschmidt process; Mond's process

4. Mond's process; Goldschmidt process