Chemistry 12 Chapter 6 General Principles and Processes of Isolation of Elements Part 6 (For CBSE, ICSE, IAS, NET, NRA 2022)

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VI. Assertion and Reason Type

Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

(i) Both assertion and reason are true and reason is the correct explanation of assertion.

(ii) Both assertion and reason are true but reason is not the correct explanation of assertion.

(iii) Assertion is true but reason is false.

(iv) Assertion is false but reason is true.

(v) Assertion and reason both are wrong.

Question 50:

Assertion: Nickel can be purified by Mond process.

Reason: is a volatile compound which decomposes at to give pure .

Answer: (i)

Question 51:

Assertion: Zirconium can be purified by Van Arkel method

Reason: is volatile and decomposes at .

Answer: (i)

Question 52:

Assertion: Sulphide ores are concentrated by Froth Flotation method.

Reason: Cresols stabilise the froth in Froth Flotation method.

Answer: (ii)

Question 53:

Assertion: Zone refining method is very useful for producing semiconductors.

Reason: Semiconductors are of high purity

Answer: (ii)

Question 54:

Assertion: Hydrometallurgy involves dissolving the ore in a suitable reagent followed by precipitation by a more electropositive metal.

Reason: Copper is extracted by hydrometallurgy.

Answer: (ii)

VII. Long Answer Type

Question 55:

Explain the following:

(a) is a better reducing agent below whereas is a better reducing agent above .

(b) Generally sulphide ores are converted into oxides before reduction.

(c) Silica is added to the sulphide ore of copper in the reverberatory furnace.

(d) Carbon and hydrogen are not used as reducing agents at high temperatures.

(e) Vapour phase refining method is used for the purification of .

Answer:

(a) Hint: Use Ellingham diagram (b)

Hint: Oxides are easier to reduce. See Ellingham diagram.

(c) Hint: Sulphide ore of copper contains iron as impurity which is removed as iron silicate (slag)

(d) Hint: Carbon and hydrogen react with metals at high temperature to form carbides and hydrides respectively.

(e) Hint: Ti reacts with iodine to form volatile TiI4 which decomposes at high temperature to give extra pure titanium.