NEET General Principles and Processes of Isolation of Elements PYQs & Practice Questions

10 free NEET Chemistry questions on General Principles and Processes of Isolation of Elements, starting with previous year questions (2017–2023). Tap “Show answer” to check each one. No login needed.

Topics: Concentration of Ores · Thermodynamics of Metallurgy (Ellingham Diagram) · Refining of Metals · Extraction of Copper · Hydrometallurgy · Calcination and Roasting · Electrolytic Refining · Extraction of Aluminium · Flux and Slag Formation · Zone Refining · Thermodynamic Principles – Ellingham Diagram · Reduction Methods

1. Q1NEET 2023Extraction of Iron (Blast Furnace Reactions)

   The reaction that does NOT take place in a blast furnace between 900 K to 1500 K temperature range during extraction of iron is:

   • A. FeO + CO -> Fe + CO2
   • B. C + CO2 -> 2CO
   • C. CaO + SiO2 -> CaSiO3
   • D. Fe2O3 + CO -> 2FeO + CO2
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   Answer: C — CaO + SiO2 -> CaSiO3

   The reaction Fe2O3 + CO -> 2FeO + CO2 occurs at a lower temperature range (around 500-800 K) in the blast furnace, not in the 900 K to 1500 K range. The reactions FeO + CO -> Fe + CO2, C + CO2 -> 2CO, and CaO + SiO2 -> CaSiO3 all occur within the 900 K to 1500 K range.

2. Q2NEET 2021Metallurgy - Blast Furnace

   The maximum temperature that can be achieved in blast furnace is:

   • A. upto 5000 K
   • B. upto 1200 K
   • C. upto 2200 K
   • D. upto 1900 K
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   Answer: B — upto 1200 K

   The maximum temperature achieved in a blast furnace (used for extraction of iron) is up to 2200 K.

3. Q3NEET 2021Purification of Metals

   Which one of the following methods can be used to obtain highly pure metal which is liquid at room temperature?

   • A. Zone refining
   • B. Electrolysis
   • C. Chromatography
   • D. Distillation
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   Answer: —

   Zone refining is used to obtain highly pure metals, including those liquid at room temperature like gallium or mercury related purification processes.

4. Q4NEET 2020Properties of iron and copper metallurgy

   Identify the correct statement from the following:

   • A. Wrought iron is impure iron with 4% carbon.
   • B. Blister copper has blistered appearance due to evolution of CO2.
   • C. Vapour phase refining is carried out for Nickel by Van Arkel method.
   • D. Pig iron can be moulded into a variety of shapes.
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   Answer: C — Vapour phase refining is carried out for Nickel by Van Arkel method.

   Pig iron, obtained directly from the blast furnace, is impure but can be cast into various shapes (cast iron), making this the correct statement; wrought iron has very low (not 4%) carbon, blister copper's appearance is due to evolution of SO2 (not CO2), and Nickel is purified by the Mond process (not Van Arkel, which is used for Ti/Zr).

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5. Q5NEET 2019Industrial Processes - Matching

   Match the following: (a) Pure nitrogen (b) Haber process (c) Contact process (d) Deacon's process -- with -- (i) Chlorine (ii) Sulphuric acid (iii) Ammonia (iv) Sodium azide or Barium azide. Which of the following is the correct option?

   • A. a-iii, b-iv, c-ii, d-i
   • B. a-iv, b-iii, c-ii, d-i
   • C. a-i, b-ii, c-iii, d-iv
   • D. a-ii, b-iv, c-i, d-iii
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   Answer: A — a-iii, b-iv, c-ii, d-i

   Pure nitrogen is obtained from thermal decomposition of sodium azide or barium azide (a-iv). The Haber process produces ammonia (b-iii). The Contact process produces sulphuric acid (c-ii). Deacon's process produces chlorine (d-i).

6. Q6NEET 2019Identification of Ores

   Which one is malachite from the following?

   • A. Fe3O4
   • B. CuCO3.Cu(OH)2
   • C. CuFeS2
   • D. Cu(OH)2
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   Answer: A — Fe3O4

   Malachite is a copper ore with the formula CuCO3.Cu(OH)2 (basic copper carbonate). Fe3O4 is magnetite (an iron ore), CuFeS2 is chalcopyrite (a copper-iron ore), and Cu(OH)2 is not a naturally occurring ore name.

7. Q7NEET 2017Extraction of gold and silver

   Extraction of gold and silver involves leaching with CN- ion. Silver is later recovered by:

   • A. distillation
   • B. zone refining
   • C. displacement with Zn
   • D. liquation
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   Answer: B — zone refining

   After leaching gold/silver ore with CN- to form the soluble [M(CN)2]- complex, the metal is recovered by displacement using a more reactive metal, zinc, via the reaction 2[Ag(CN)2]- + Zn -> [Zn(CN)4]2- + 2Ag.

8. Q8Concentration of Ores

   Which method of concentration is used to separate sulphide ores from gangue?

   • A. Gravity separation
   • B. Magnetic separation
   • C. Froth flotation
   • D. Leaching
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   Answer: B — Magnetic separation

   Froth flotation is used to concentrate sulphide ores. The ore particles are wetted by pine oil (collector) and float as froth, while gangue particles sink in water. This method exploits the difference in wettability between ore and gangue.

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9. Q9Thermodynamics of Metallurgy (Ellingham Diagram)

   According to the Ellingham diagram, coke (carbon) can reduce Fe₂O₃ at high temperatures but cannot reduce Al₂O₃ under normal conditions. What is the primary reason for this?

   • A. The ΔG° for formation of Al₂O₃ is always more negative than that for CO₂
   • B. The Ellingham line for CO/CO₂ crosses the line for Fe₂O₃ at a feasible temperature but never crosses the Al₂O₃ line
   • C. Carbon forms a stable carbide with aluminium, making reduction impossible
   • D. Aluminium oxide has a higher melting point than iron oxide
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   Answer: A — The ΔG° for formation of Al₂O₃ is always more negative than that for CO₂

   In the Ellingham diagram, a reducing agent can reduce an oxide only if its oxidation line lies below the oxide's line (more negative ΔG°). The line for C→CO/CO₂ crosses Fe₂O₃ at ~983 K (making reduction feasible), but the line for C never goes below the Al₂O₃ line under practical conditions, so carbon cannot reduce Al₂O₃. Hence, electrolytic reduction is used for aluminium.

10. Q10Refining of Metals

    In the Van Arkel method of refining, titanium is first converted to TiI₄ and then decomposed on a hot tungsten filament. What type of reaction makes this process work?

    • A. The iodide is more stable at high temperatures than at low temperatures
    • B. TiI₄ is volatile and decomposes at high temperature, depositing pure Ti
    • C. Tungsten acts as a reducing agent to displace titanium from TiI₄
    • D. Iodine reacts with impurities but not with pure titanium at high temperatures
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    Answer: A — The iodide is more stable at high temperatures than at low temperatures

    In the Van Arkel method, impure Ti reacts with I₂ at ~500 K to form volatile TiI₄. This vapour is then decomposed on a hot tungsten filament (~1700 K), depositing pure titanium and releasing I₂ which is recycled. The process exploits the thermal instability of metal iodides at very high temperatures.