NEET Chemistry: Metallurgy questions with solutions

Q1. In the atmosphere of industrial smog, copper corrodes to form: This question has multiple correct options

1. Basic copper carbonate
2. Copper sulphide
3. Basic copper sulphate
4. copper oxide

Answer: Basic copper carbonate

In polluted, moist air containing carbon dioxide, copper slowly forms a green protective patina of basic copper carbonate. This is the common corrosion product of copper in atmospheric conditions.

Q2. The idea of froth floatation method came from a person \( X \) and this method is related to the process \( Y \) of ores. \( X \) and Y, respectively, are:

1. fisher woman and concentration
2. washer man and reduction
3. washer woman and concentration
4. fisher man and reduction

Answer: washer woman and concentration

Froth flotation was inspired by the washing action used by a washer woman, where lighter impurities are separated from heavier material. In metallurgy, it is a concentration method because it increases the proportion of the desired ore mineral.

Q3. Refining of aluminium is done by

1. electrolysis
2. distillation
3. sedimentation
4. oxidation

Answer: electrolysis

Aluminium is refined by electrolysis because this method can separate and purify metals using an electric current. Distillation, sedimentation, and oxidation are not the standard refining methods for aluminium.

Q4. Roasting is carried out to This question has multiple correct options

1. convert sulphide ore to oxide
2. remove water of hydration
3. melt the ore
4. remove carbon and sulphur impurities

Answer: convert sulphide ore to oxide

Roasting means strongly heating an ore in the presence of excess air/oxygen. For sulphide ores, this converts the sulphide into the corresponding oxide, which is easier to reduce later.

Q5. In the extraction of aluminium by electrolytic process, cryolite is added to

1. lower the melting point of alumina
2. increase the electrical conductivity
3. minimise the anode effect
4. remove impurities from alumina

Answer: lower the melting point of alumina

Cryolite is added in the Hall-Héroult process mainly to reduce the melting point of alumina, which allows electrolysis to occur at a much lower temperature. It also improves conductivity, but the key reason asked here is the melting-point reduction.

Q6. Metal oxides are reduced to metal by:

1. electrolytic reduction
2. liquation
3. distillation
4. none of the above

Answer: electrolytic reduction

Highly reactive metal oxides are too stable to be reduced by common chemical reducing agents like carbon. They are obtained by electrolytic reduction, where electric current drives the oxide to release the metal.

Q7. Forth floatation process of concentration is based on the:

1. preferential wetting properties with the frothing agent and water
2. difference in the specific gravities of gangue and ore particles
3. difference in solubility of ganaue and ore particles in frothing agent and water
4. difference in reactivity of gangue and ore particles with water and frothing agent.

Answer: preferential wetting properties with the frothing agent and water

Froth flotation works because one component is preferentially wetted by water while the other is preferentially wetted by the frothing agent and air bubbles. This difference in wetting behavior lets the desired particles rise with the froth.

Q8. Sulphides ores are converted to oxides before reduction. This is explained on the basis of which of the following?

1. Sulphides cannot be reduced easily while oxides can be reduced easily.
2. Sulphides decompose on reduction hence they are fixed converted to oxides.
3. Sulphide ores have higher melting points than oxides.
4. Oxides are more stable than sulphides hence easy to reduce.

Answer: Sulphides decompose on reduction hence they are fixed converted to oxides.

Sulphide ores are first roasted to oxides because sulphides tend to decompose or behave poorly under direct reduction conditions. The oxide form is then much easier to reduce to the metal.

Q9. Assertion Metals of high impurity are obtained by zone-refining. Reason Impurities in the ore are more soluble in the metal than in the pure metal Choose the correct option.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason is correct

Answer: Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Zone refining works because impurities are more soluble in the molten zone than in the solid metal, so they concentrate in the moving liquid and are carried to one end. This makes the purified portion of the metal highly pure, so the assertion is correct and the reason explains it.