NEET Previous Year Questions (2014-2024): General Principles & Processes of Isolation of Elements (Old NCERT) | Chemistry Class 12 PDF Download

Q.1. The reaction that does NOT take place in a blast furnace between 900 K to 1500 K temperature range during extraction of iron is:        (2023)
A: Fe₂O₃ + CO → 2FeO + CO₂ 
B: FeO + CO → Fe + CO₂
C: C + CO₂ → 2CO
D: CaO + SiO₂ → CaSiO₃
Ans: A
At 900 -1500 K (higher temperature range in the blast furnace)
Reaction which take place are :–
C + CO₂ → 2CO
FeO + CO → Fe + CO₂
CaO + SiO₂ → CaSiO₃ (Slag formation)
Fe₂O₃ + CO → 2FeO + CO₂ → This take place at 500 - 800 K.

Q.2. Match List-I with List-II.    (2022)

A: (a) – (iii), (b) – (i), (c) – (iv), (d) – (ii)
B: (a) – (i), (b) – (iii), (c) – (ii), (d) – (iv)
C: (a) – (i), (b) – (ii), (c) – (iii), (d) – (iv)
D: (a) – (iii), (b) – (i), (c) – (ii), (d) – (iv)
Ans: D

Haematite    -    Fe₂O₃

Magnetite    -    Fe₃O₄

Calamine    -    ZnCO₃

Kaolinite    -    [Ah(OH)₄ShO₅]

 
Q.3. Which one of the following methods can be used to obtain highly pure metal which is liquid at room temperature?     (2021)
A: Distillation
B: Zone refining
C: Electrolysis
D: Chromatography
Ans: A
At room temperature Hg is liquid and it is purified by 'Distillation method'.

Q.4. The maximum temperature that can be achieved in blast furnace is :     (2021)
A: Upto 1900 K
B: Upto 5000 K
C: Upto 1200 K
D: Upto 2200 K
Ans: D
The maximum temperature that can be achieved in blast furnace is upto 2200 K.

Q.5. Paper chromatography is an example of :     (2020)
A: Thin layer chromatography 
B: Column chromatography 
C: Adsorption chromatography 
D: Partition chromatography
Ans: D
It is an example of partition chromatography as mixture of substance are separated by partition.

Q.6. Identify the correct statement from the following:      (2020)
A: Vapour phase refining is carried out for Nickel by Van Arkel method.
B: Pig iron can be moulded into a variety of shapes.
C: Wrought iron is impure iron with 4% carbon.
D: Blister copper has blistered appearance due to evolution of CO₂.
Ans: B
A. Vapour phase refining is carried out for nickel by Mond process.
B. Pig iron is molten iron obtained from blast furnace after smelting it can be moulded into variety of shapes.
C. Wrought iron is the purest form of iron which has less than 4% carbon.
D. Blister copper has blistered appearance due to evolution of SO₂.

Q.7. Which one is malachite from the following?    (2019)
A: CuFeS₂
B: Cu(OH)₂
C: Fe₃O₄
D: CuCO₃.Cu(OH)₂
Ans: D
Malachite : CuCO₃.Cu(OH)₂ (Green colour)

Q.8. The process of heating the concentrated ore in a limited supply of air or in the absence of air is known as:    (2017)
A: Roasting
B: Leaching
C: Calcination
D: Cupellation
Ans: C
In the process of metallurgy, Calcination is used for the concentration of ore to oxide. It is a process of heating an ore in a limited supply of air. If the ore is heated in the presence of excess of air then its ia known as roasting. Generally carbonate ores are calcined and hence carbon dioxide is given out.

Q.9. Extraction of gold and silver involes leaching with CN^- ion. Silver is later recovered by :-    (2017)
A: Distillation
B: Zone refining
C: Displacement with Zn
D: Liquation
Ans: C


Q.10. Match items of Column I with the items of Column II and assign the correct code :    (2016)

     (a) (b) (c) (d)
A: (iii) (iv) (v) (i)
B: (iv) (ii) (iii) (i)
C: (ii) (iii) (i) (v)
D: (i) (ii) (iii) (iv)
Ans: B
(iv) (ii) (iii) (i)
Cyanide process is used for extracting Au (gold) from low-grade ore by converting the Au to the water soluble coordination complex.
Froth flotation process is used for the dressing of sulphide ore such ZnS.
Electrolytic reduction is used for the extraction of Al. The extraction of aluminium is carried out in a steel tank lined inside with graphite. Here graphite used serves as a cathode.
Zone refining is used for ultra pure Ge element. An ingot of Ge is first purified by zone refining. Then a small amount of antimony is placed in the molten zone which is passed through the pure Ge with the proper choice of rate of heating and other variables.

Q.11. "Metals are usually not found as nitrates in their ores".
Out of the following two (a and b) reasons which is / are true for the above observation ?
(a) Metal nitrates are highly unstable
(b) Metal nitrates are highly soluble in water.    (2015)
A: a is true but b is false
B: a and b are true
C: a and b are false
D: a is false but b is true
Ans: D
Metal nitrates are usually not found as nitrates in their ores because they are highly soluble in water.