Extraction of Metals (Roasting, Calcination, Reduction, Electrolysis) MCQs

Q1. Which of the following is obtained simply by heating its ore in air, without reduction?

• A.mercury (from cinnabar)
• B.iron (from haematite)
• C.sodium (from rock salt)
• D.aluminium (from bauxite)

Answer: A. mercury (from cinnabar)

The principle at play: Oxidation = addition of O or loss of H or electrons; reduction = addition of H or loss of O or gain of electrons; tag each species: the one losing e- is oxidised => apply this rule to the stem reaction to pick the answer = mercury (from cinnabar). Connecting concept to answer: Correct. Why the other options fail: option B) 'iron (from haematite)' fails since Iron needs reduction with carbon; option C) 'sodium (from rock salt)' is incorrect: Sodium needs electrolysis; option D) 'aluminium (from bauxite)' is wrong because Aluminium needs electrolysis. Thus the correct option is A) mercury (from cinnabar).

Q2. Consider the following statements about extraction of metals: (I) Roasting is done for sulphide ores in excess air. (II) Calcination releases carbon dioxide from carbonate ores. (III) Sodium is extracted by reducing its oxide with carbon. Which of the above statement(s) is/are correct?

• A.None of these
• B.Only I
• C.Only III
• D.Only I and II

Answer: D. Only I and II

We are told: the data stated in the problem. What we must find: the unknown asked in the stem. The relation that links these is - therefore the answer = Only I and II. This is the equation that links the given quantities to the unknown (chemistry, chapter 'Metals and Non-metals'). Why this works - acid + carbonate -> salt + water + CO2(g), e.g. So the answer is D) Only I and II. The other choices: option A) 'None of these' fails since Re-check each statement individually; option B) 'Only I' misses the point - Re-check each statement individually; option C) 'Only III' misses the point - Re-check each statement individually.

Q3. Which step comes immediately after obtaining the impure metal in metallurgy?

• A.roasting the ore
• B.concentration of the ore
• C.mining the ore
• D.refining (purification) of the metal

Answer: D. refining (purification) of the metal

NCERT fact (chemistry, chapter 'Metals and Non-metals'): Metals are lustrous, malleable, ductile, conductors and lose electrons to form cations; non-metals are dull, brittle, insulators and gain electrons to form anions; matching the listed property to this dichotomy => only one option fits; hence answer = refining (purification) of the metal. Why option D fits - Correct. Distractor analysis: option A) 'roasting the ore' doesn't hold - Roasting precedes reduction; option B) 'concentration of the ore' is incorrect: Concentration is done before reduction. Final answer - D) refining (purification) of the metal.