${\rm{ZnS}} + {\rm{BaS}}{{\rm{O}}_4}$

On igniting ${\rm{F}}{{\rm{e}}_2}{{\rm{O}}_3}$ at 14000$^\circ $C, the product obtained is

${\rm{F}}{{\rm{e}}_2}{{\rm{O}}_3}$ melt

${\rm{F}}{{\rm{e}}_2}{{\rm{O}}_3}$

Metallic silver may be obtained from ${\rm{AgCl}}$ by

Fusing it with ${\rm{N}}{{\rm{a}}_2}{\rm{C}}{{\rm{O}}_3}$

Heating it in the current of ${{\rm{H}}_2}$

GENERAL PRINCIPLES AND PROCESSES OF ISOLATION OF ELEMENTS MCQs for NEET UG CHEMISTRY — Easy, Page 2

31 Easy

31 of 69Question permalink

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Which is the chief ore of copper?

View answer and explanation

Correct option: B

Copper pyrites

Option B is correct because Copper pyrites (

CuFeS_2

) is the most abundant and chief ore of copper.

Solution approach

Correct Answer + Core Reason: Copper pyrites. Copper pyrites ( $CuFeS_2$ ) is the chief ore of copper.

Step-by-Step Solution:

Step 1: Recall the common ores of copper.

Step 2: Identify the chief ore of copper.

Step 3: Analyze each option:
- Galena (PbS) is an ore of lead.
- Copper pyrites ( $CuFeS_2$ ) is the chief ore of copper.
- Sphalerite (ZnS) is an ore of zinc.
- Siderite ( $FeCO_3$ ) is an ore of iron.

Why other options are wrong:
- Option A: Galena is an ore of lead.
- Option C: Sphalerite is an ore of zinc.
- Option D: Siderite is an ore of iron.

Key Concepts:
- Ores of metals
- Copper ores

Memory Aids:
- Copper pyrites contains copper, iron, and sulfur.

Quick Tips:
- Memorize the common ore formulas.

32 Easy

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In the extraction of copper from its sulphide ore, the metal is finally obtained by the reduction of cuprous oxide with:

View answer and explanation

Correct option: C

Copper(I) sulphide

(\mathrm{C}{\mathrm{u}_2}\mathrm{S)}

Option C (Copper(I) sulphide

(\mathrm{C}{\mathrm{u}_2}\mathrm{S)}

) is correct because the final step in copper extraction from sulfide ores involves the reduction of cuprous oxide (

Cu_2O

) by cuprous sulfide (

Cu_2S

).

Solution approach

Correct Answer + Core Reason: $Cu_2S$ reduces $Cu_2O$ to obtain copper.

Step-by-Step Solution:

Step 1: Recall the final step in copper extraction.

Step 2: Cuprous oxide ( $Cu_2O$ ) is reduced by cuprous sulfide ( $Cu_2S$ ) to produce copper.

Step 3: $2Cu_2O + Cu_2S \rightarrow 6Cu + SO_2$

Why other options are wrong:
- Option A: Iron sulfide (FeS) is not used in the final reduction step.
- Option B: Carbon monoxide (CO) is not used in the final reduction step.
- Option D: Sulphur dioxide ( $SO_2$ ) is a product of the reaction, not a reactant.

Key Concepts:
- Copper extraction
- Reduction of metal oxides

Memory Aids:
- $Cu_2S$ helps $Cu_2O$ become pure copper.

Quick Tips:
- Know the specific reducing agents used in metal extraction.

33 Easy

33 of 69Question permalink

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From gold amalgam, gold may be recovered by:

View answer and explanation

Correct option: C

Distillation

Option C (Distillation) is correct because mercury has a low boiling point and can be easily separated from gold by heating the amalgam.

Solution approach

Correct Answer + Core Reason: Distillation. Mercury is volatile and can be separated from gold by heating the amalgam.

Step-by-Step Solution:

Step 1: Define gold amalgam. Gold amalgam is an alloy of gold and mercury.

Step 2: Consider the properties of mercury. Mercury has a relatively low boiling point (357 $^\circ$ C) compared to gold (2856 $^\circ$ C).

Step 3: Explain the distillation process. Heating the amalgam to a temperature above mercury's boiling point causes the mercury to vaporize, leaving the gold behind.

Why other options are wrong:
- Option A: Addition of $\mathrm{Zn}$ metal. Adding zinc would not effectively separate gold from mercury. It might form another alloy, but it wouldn't isolate the gold.
- Option B: Electrolytic refining. Electrolytic refining is used for purifying metals, but it's not the most efficient method for separating gold from mercury in an amalgam. Distillation is simpler and more direct.
- Option D: Dissolving $Hg\;in\;\mathrm{HN}{\mathrm{O}_3}$ . Dissolving mercury in nitric acid would separate mercury from gold, but it's not the most direct method. Distillation is preferred because it's simpler and avoids the use of chemicals.

Key Concepts:
- Amalgam
- Distillation
- Boiling Point
- Volatility

Memory Aids:
- Distillation: \"Distill\" - to separate by boiling point.

Quick Tips:
- Remember that distillation is effective for separating substances with significantly different boiling points.

34 Easy

34 of 69Question permalink

Remembering +4 | -1

Anglesite is an ore of:

View answer and explanation

Correct option: D

\mathrm{Pb}

Option D (

\mathrm{Pb}

) is correct because anglesite is a lead sulfate mineral (

\mathrm{PbSO_4}

), making it an ore of lead.

Solution approach

Correct Answer + Core Reason: $\mathrm{Pb}$ . Anglesite is an ore of lead.

Step-by-Step Solution:

Step 1: Recall the chemical composition of anglesite: Anglesite is lead sulfate ( $\mathrm{PbSO_4}$ ).

Step 2: Relate the composition to the metal: Since anglesite contains lead (Pb), it is an ore of lead.

Step 3: Evaluate the other options: Cadmium, nickel, and antimony are not primary components of anglesite.

Step 4: Conclusion: Lead (Pb) is the correct answer.

Why other options are wrong:
- **Option A ( $\mathrm{Cd}$ ): Anglesite does not contain cadmium.
- Option B ( $\mathrm{Ni}$ ): Anglesite does not contain nickel.
- Option C ( $\mathrm{Sb}$ ): Anglesite does not contain antimony.

Key Concepts:
- Ore identification
- Chemical composition of minerals
- Lead metallurgy

Memory Aids:
- Anglesite = Lead Sulfate = Lead Ore

Quick Tips:**
- Know the chemical formulas of common ores and the metals they contain.

35 Easy

35 of 69Question permalink

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Statement – I: Ellingham diagram explains the kinetics of reduction process.

Statement – II: Hydraulic washing, a method of concentration of ore is based on the
differences in gravities of the ore and the gangue.

In the light of above statements choose the correct option among the following.

View answer and explanation

Correct option: D

Statement – I is false but statement – II is true

Option D (Statement – I is false but statement – II is true) is correct because Ellingham diagrams relate to thermodynamics, not kinetics, and hydraulic washing separates based on gravity differences.

Solution approach

Correct Answer + Core Reason: Statement – I is false but statement – II is true. Ellingham diagrams relate to thermodynamics, and hydraulic washing is based on gravity differences.

Step-by-Step Solution:

Step 1: Analyze Statement I: Ellingham diagram explains the kinetics of the reduction process.\nEllingham diagrams show the Gibbs free energy change ( $\Delta G$ ) for the formation of metal oxides as a function of temperature. They provide information about the thermodynamic feasibility of reduction reactions, not the kinetics (rate) of the reactions. Therefore, Statement I is false.

Step 2: Analyze Statement II: Hydraulic washing, a method of concentration of ore is based on the differences in gravities of the ore and the gangue.\nHydraulic washing is a method used to concentrate ores by separating them from gangue (impurities) based on differences in their densities (specific gravities). The heavier ore particles settle down, while the lighter gangue particles are washed away by a stream of water. Therefore, Statement II is true.

Why other options are wrong:
- Option A: Both statements are not true because Statement I is false.
- Option B: Both statements are not false because Statement II is true.
- Option C: Statement I is not true and Statement II is not false.

Key Concepts:
- Ellingham Diagram: Thermodynamic feasibility of reduction reactions.
- Hydraulic Washing: Separation based on density differences.

Memory Aids:
- Ellingham: "Energy" and "Thermodynamics".
- Hydraulic Washing: "Heavy" ore settles, "Light" gangue washes away.

Quick Tips:
- Remember that Ellingham diagrams deal with thermodynamics, not kinetics.
- Hydraulic washing relies on density differences.

36 Easy

36 of 69Question permalink

Remembering +4 | -1

Chinese white is:

View answer and explanation

Correct option: D

ZnO

Option D is correct because Chinese white is the common name for Zinc oxide (ZnO), which is used as a pigment.

Solution approach

Correct Answer + Core Reason: ZnO. Zinc oxide is known as Chinese white.

Step-by-Step Solution:

Step 1: Recall the common names of zinc compounds.

Step 2: Zinc oxide (ZnO) is known as Chinese white and is used as a pigment.

Step 3: Compare the given options with the known names of zinc compounds.

Why other options are wrong:
- Option A: ZnS is zinc sulfide.
- Option B: $ZnCO_3$ is zinc carbonate.
- Option C: $ZnS + BaSO_4$ is lithopone.

Key Concepts:
- Common names of chemical compounds
- Zinc compounds

Memory Aids:
- Chinese white is a white pigment made of zinc oxide.

Quick Tips:
- Memorize the common names of important chemical compounds.

37 Easy

37 of 69Question permalink

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In which metal’s metallurgical process carbon is used for reduction of metal oxides?

View answer and explanation

Correct option: C

Fe

Option C is correct because carbon is commonly used as a reducing agent in the metallurgical process of iron (Fe) extraction from its oxides.

Solution approach

Correct Answer + Core Reason: Fe. Carbon is used for the reduction of iron oxides in the metallurgical process of iron extraction.

Step-by-Step Solution:

Step 1: Consider the options: We need to identify the metal whose oxide is reduced by carbon.

Step 2: Sodium (Na): Sodium is extracted by electrolysis of its molten chloride because it is a highly electropositive metal.

Step 3: Silver (Ag): Silver can be extracted by cyanide process followed by reduction with zinc or by direct heating of its oxide.

Step 4: Iron (Fe): Iron is extracted from its oxides (like $Fe_2O_3$ ) in a blast furnace using carbon as a reducing agent.

Step 5: Mercury (Hg): Mercury is extracted by heating its sulfide ore (cinnabar, HgS) in air.

Step 6: Conclusion: Carbon is used in the extraction of Iron (Fe).

Why other options are wrong:
- Option A: Sodium is extracted by electrolysis, not carbon reduction.
- Option B: Silver is extracted by cyanide process or direct heating, not primarily by carbon reduction.
- Option D: Mercury is extracted by heating its sulfide ore in air.

Key Concepts:
- Extraction of Metals
- Reduction Processes
- Carbon as a Reducing Agent

Memory Aids:
- Remember that carbon is a common reducing agent for many metal oxides, especially iron.

Quick Tips:
- Know the common reducing agents used for different metals.

38 Easy

38 of 69Question permalink

Understanding +4 | -1

On igniting

\mathrm{F}{\mathrm{e}_2}{\mathrm{O}_3}

at 14000

^\circ

C, the product obtained is

View answer and explanation

Correct option: D

Metallic iron

Option D (Metallic iron) is correct because at very high temperatures, iron oxide decomposes to form metallic iron and oxygen.

Solution approach

Correct Answer + Core Reason: Metallic iron. At very high temperatures, $\mathrm{F}{\mathrm{e}_2}{\mathrm{O}_3}$ decomposes to metallic iron.

Step-by-Step Solution:

Step 1: Consider the thermal stability of metal oxides. Metal oxides can decompose at high temperatures, releasing oxygen.

Step 2: Write the decomposition reaction for $\mathrm{F}{\mathrm{e}_2}{\mathrm{O}_3}$ . $\mathrm{F}{\mathrm{e}_2}{\mathrm{O}_3} \rightarrow 2\mathrm{Fe} + \frac{3}{2}\mathrm{O}_2$

Step 3: Analyze the given temperature. 14000 $^\circ$ C is a very high temperature, sufficient to cause the decomposition of $\mathrm{F}{\mathrm{e}_2}{\mathrm{O}_3}$ .

Why other options are wrong:
- Option A: $\mathrm{F}{\mathrm{e}_2}{\mathrm{O}_3}$ melt. While $\mathrm{F}{\mathrm{e}_2}{\mathrm{O}_3}$ might melt, the primary process at such a high temperature is decomposition, not just melting. The decomposition produces metallic iron.
- Option B: FeO. FeO can be an intermediate in the reduction of $\mathrm{F}{\mathrm{e}_2}{\mathrm{O}_3}$ , but at 14000 $^\circ$ C, the reduction proceeds further to metallic iron.
- Option C: $\mathrm{F}{\mathrm{e}_2}{\mathrm{O}_3}$ . $\mathrm{F}{\mathrm{e}_2}{\mathrm{O}_3}$ is the reactant, not the product at this high temperature. It decomposes.

Key Concepts:
- Thermal Decomposition
- Metal Oxides
- Reduction

Memory Aids:
- High temperature often leads to decomposition.

Quick Tips:
- Remember that metal oxides can be reduced to their metallic form at high temperatures.

39 Easy

39 of 69Question permalink

Remembering +4 | -1

Which is not a basic flux?

View answer and explanation

Correct option: C

\mathrm{Si}{\mathrm{O}_2}

Option C (SiO2) is correct because silicon dioxide (

SiO_2

) is an acidic flux, while the others are basic fluxes.

Solution approach

Correct Answer + Core Reason: $\mathrm{Si}{\mathrm{O}_2}$ . Silicon dioxide is an acidic flux, not a basic flux.

Step-by-Step Solution:

Step 1: Define Flux: A flux is a substance used to promote fusion, especially of metals or minerals.

Step 2: Define Basic Flux: A basic flux is used to remove acidic impurities during smelting.

Step 3: Define Acidic Flux: An acidic flux is used to remove basic impurities during smelting.

Step 4: Consider $\mathrm{CaC}{\mathrm{O}_3}$ : Calcium carbonate decomposes to CaO, a basic oxide, making it a basic flux.

Step 5: Consider $\mathrm{CaO}$ : Calcium oxide is a basic oxide and acts as a basic flux.

Step 6: Consider $\mathrm{Si}{\mathrm{O}_2}$ : Silicon dioxide is an acidic oxide and acts as an acidic flux.

Step 7: Consider $\mathrm{MgO}$ : Magnesium oxide is a basic oxide and acts as a basic flux.

Why other options are wrong:
- Option A: $\mathrm{CaC}{\mathrm{O}_3}$ is a basic flux.
- Option B: $\mathrm{CaO}$ is a basic flux.
- Option D: $\mathrm{MgO}$ is a basic flux.

Key Concepts:
- Flux (Acidic and Basic)
- Smelting

Memory Aids:
- Acidic Flux: Removes Basic Impurities (e.g., $SiO_2$ )
- Basic Flux: Removes Acidic Impurities (e.g., CaO, MgO)

Quick Tips:
- Remember that acidic fluxes react with basic impurities and vice versa.
- Know common examples of acidic and basic fluxes.

40 Easy

40 of 69Question permalink

Remembering +4 | -1

Which is not an ore of iron?

View answer and explanation

Correct option: C

Cassiterite

Option C is correct because Cassiterite (

SnO_2

) is an ore of tin, not iron.

Solution approach

Correct Answer + Core Reason: Cassiterite. Cassiterite is an ore of tin, not iron.

Step-by-Step Solution:

Step 1: Recall the common ores of iron.

Step 2: Identify the ore that is not an ore of iron.

Step 3: Analyze each option:
- Haematite ( $Fe_2O_3$ ) is an ore of iron.
- Magnetite ( $Fe_3O_4$ ) is an ore of iron.
- Cassiterite ( $SnO_2$ ) is an ore of tin.
- Limonite ( $Fe_2O_3 \cdot nH_2O$ ) is an ore of iron.

Why other options are wrong:
- Option A: Haematite is an ore of iron.
- Option B: Magnetite is an ore of iron.
- Option D: Limonite is an ore of iron.

Key Concepts:
- Ores of metals
- Iron ores

Memory Aids:
- Cassiterite contains tin (Sn).

Quick Tips:
- Memorize the common ore formulas.

41 Easy

41 of 69Question permalink

Understanding +4 | -1

Melting of Zn metal and then pouring it into cold water gives:

View answer and explanation

Correct option: B

Granulated Zn

Option B (Granulated Zn) is correct because rapidly cooling molten zinc by pouring it into cold water results in the formation of small, irregular granules.

Solution approach

Correct Answer + Core Reason: Granulated Zn. Rapid cooling of molten zinc forms granules.

Step-by-Step Solution:

Step 1: Melting zinc converts it from a solid to a liquid state.

Step 2: Pouring the molten zinc into cold water causes rapid cooling and solidification.

Step 3: This rapid cooling prevents the formation of large crystals, resulting in the formation of small, irregular granules of zinc.

Why other options are wrong:
- Option A: Zn dust is produced by vaporizing zinc and then condensing it rapidly, not by pouring molten zinc into water.
- Option C: Hard Zn metal would be formed by slow cooling, allowing for crystal growth.
- Option D: Soft Zn metal is a general property of zinc, not specifically related to this process.

Key Concepts:
- Metallurgy
- Solidification
- Cooling rates

Memory Aids:
- Rapid cooling leads to smaller particles (granules).

Quick Tips:
- Consider the effect of cooling rate on the resulting solid structure.

42 Easy

42 of 69Question permalink

Understanding +4 | -1

In zone refining method, the molten zone :

View answer and explanation

Correct option: C

contains more impurity than the original

Option C (contains more impurity than the original) is correct because in zone refining, impurities are more soluble in the molten zone and thus concentrate there as the zone moves.

Solution approach

Correct Answer + Core Reason: contains more impurity than the original. Impurities are more soluble in the molten zone.

Step-by-Step Solution:

Step 1: Recall the zone refining method: Zone refining is a purification technique where a molten zone is passed along a solid material.

Step 2: Explain the impurity distribution: Impurities tend to be more soluble in the molten zone than in the solid phase. As the molten zone moves, it carries the impurities along with it, concentrating them in the molten zone.

Step 3: Evaluate the other options: The molten zone does not contain only purified metal, and it doesn't move to either side randomly.

Step 4: Conclusion: The molten zone contains more impurity than the original material.

Why other options are wrong:
- Option A (contains impurities): This is partially correct, but option C is more accurate as it specifies *more* impurity.
- Option B (contains puriﬁed metal only): The molten zone contains impurities, not just purified metal.
- Option D (moves to either side): The molten zone moves in a specific direction to concentrate impurities at one end.

Key Concepts:
- Zone refining
- Purification techniques
- Impurity distribution

Memory Aids:
- Zone Refining = Impurities in Molten Zone

Quick Tips:
- Understand the principle of impurity segregation in zone refining.

43 Easy

43 of 69Question permalink

Understanding +4 | -1

Which is not an organic compound?

View answer and explanation

Correct option: D

Ammonium cyanate

Option D (Ammonium cyanate) is correct because it is an inorganic compound, while the others are organic.

Solution approach

Correct Answer + Core Reason: Ammonium cyanate is not an organic compound.

Step-by-Step Solution:

Step 1: Organic compounds are generally defined as compounds containing carbon-hydrogen bonds.

Step 2: Hexane ( $C_6H_{14}$ ), urea ( $CO(NH_2)_2$ ), and spirit (ethanol, $C_2H_5OH$ ) all contain carbon-hydrogen bonds.

Step 3: Ammonium cyanate ( $NH_4OCN$ ) does not contain direct carbon-hydrogen bonds and is considered an inorganic compound.

Why other options are wrong:
- Option A: Hexane is an alkane and contains carbon-hydrogen bonds.
- Option B: Urea contains carbon-hydrogen bonds (indirectly through the amine groups).
- Option C: Spirit (typically ethanol) contains carbon-hydrogen bonds.

Key Concepts:
- Organic compounds
- Carbon-hydrogen bonds
- Inorganic compounds

Memory Aids:
- Organic = Carbon-based

Quick Tips:
- Look for carbon-hydrogen bonds to identify organic compounds.

44 Easy

44 of 69Question permalink

Understanding +4 | -1

For purification of alumina, the modern processes most useful when (i) the impurity present is a lot iron oxides and (ii) the impurity present is a lot of silica, are

View answer and explanation

Correct option: D

For (i) Baeyer’s process; for (ii) Serpeck’s process

Option D (For (i) Baeyer’s process; for (ii) Serpeck’s process) is correct because Baeyer's process is suitable for removing iron oxides, and Serpeck's process is used to remove silica.

Solution approach

Correct Answer + Core Reason: Baeyer's process for iron oxides and Serpeck's process for silica.

Step-by-Step Solution:

Step 1: Consider the impurities and the appropriate purification method:
- (i) Iron oxides: Baeyer's process is used to remove iron oxides from bauxite. It involves dissolving alumina in concentrated NaOH, leaving iron oxides as insoluble impurities.
- (ii) Silica: Serpeck's process is used to remove silica from bauxite. It involves heating bauxite with coke and nitrogen, converting alumina to aluminum nitride (AlN) and silica to silicon monoxide (SiO), which is volatile.

Why other options are wrong:
- Option A: For (i) the Hall’s process; for (ii) Baeyer’s process - Incorrect because Hall's process is for electrolysis, not impurity removal.
- Option B: For (i) Serpeck’s process; for (ii) Baeyer’s process - Incorrect because Serpeck's is for silica removal, and Baeyer's is for iron oxide removal.
- Option C: For (i) Hall’ process; for (ii) Serpeck’s process - Incorrect because Hall's process is for electrolysis, not impurity removal.

Key Concepts:
- Purification of alumina
- Baeyer's process
- Serpeck's process

Memory Aids:
- Baeyer's: Iron removal
- Serpeck's: Silica removal

Quick Tips:
- Remember which process is used for which impurity.

45 Easy

45 of 69Question permalink

Remembering +4 | -1

A common metal used as reductant for the extraction of metals from their oxides is:

View answer and explanation

Correct option: B

\mathrm{Al}

Option B is correct because aluminum is a strong reducing agent and is commonly used in the extraction of metals from their oxides, especially when carbon reduction is not feasible (e.g., in the aluminothermic process).

Solution approach

Correct Answer + Core Reason: $\mathrm{Al}$ . Aluminum is a common metal used as a reductant for the extraction of metals from their oxides, especially in the aluminothermic process.

Step-by-Step Solution:

Step 1: Consider the options: We need to identify a metal commonly used as a reducing agent.

Step 2: Chromium (Cr): Chromium is sometimes used as an additive in steel, but not as a primary reducing agent for extracting other metals.

Step 3: Aluminum (Al): Aluminum is a strong reducing agent and is used in the aluminothermic process to extract metals like manganese and chromium from their oxides.

Step 4: Cobalt (Co): Cobalt is primarily used in alloys and not as a reducing agent for extracting other metals.

Step 5: Iron (Fe): Iron is extracted using carbon as a reducing agent, but it is not typically used as a reducing agent for other metals.

Step 6: Conclusion: Aluminum is the most common metal used as a reductant.

Why other options are wrong:
- Option A: Chromium is not as commonly used as aluminum for reducing metal oxides.
- Option C: Cobalt is not used as a reducing agent for metal oxides.
- Option D: Iron is reduced by carbon, and not typically used as a reducing agent for other metals' oxides.

Key Concepts:
- Reduction of Metal Oxides
- Reducing Agents
- Aluminothermic Process

Memory Aids:
- Remember that aluminum is a strong reducing agent due to its high affinity for oxygen.

Quick Tips:
- Know the common reducing agents used for different metals.

46 Easy

46 of 69Question permalink

Understanding +4 | -1

Ferric oxide in furnace is reduced by:

View answer and explanation

Correct option: C

CO

Option C (CO) is correct because in the blast furnace, carbon monoxide (CO) is the primary reducing agent that reduces ferric oxide (

Fe_2O_3

) to iron.

Solution approach

Correct Answer + Core Reason: CO reduces ferric oxide in the furnace.

Step-by-Step Solution:

Step 1: Recall the reactions in a blast furnace.

Step 2: Carbon monoxide (CO) is the main reducing agent in the blast furnace.

Step 3: $Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2$

Why other options are wrong:
- Option A: Carbon (C) reacts to form CO, which then acts as the reducing agent.
- Option B: Hydrogen ( $H_2$ ) is not the primary reducing agent in this process.
- Option D: Carbon dioxide ( $CO_2$ ) is a product of the reduction, not a reducing agent.

Key Concepts:
- Iron extraction
- Blast furnace
- Reducing agents

Memory Aids:
- CO is the "hero" in reducing iron oxide.

Quick Tips:
- Understand the chemical reactions occurring in the blast furnace.

47 Easy

47 of 69Question permalink

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The pyrolusite ore contains:

View answer and explanation

Correct option: C

Mn

Option C (Mn) is correct because pyrolusite is a manganese oxide mineral (

MnO_2

).

Solution approach

Correct Answer + Core Reason: Mn. Pyrolusite ore contains manganese ( $MnO_2$ ).

Step-by-Step Solution:

Step 1: Define Pyrolusite: Pyrolusite is a mineral consisting essentially of manganese dioxide ( $MnO_2$ ).

Step 2: Therefore, pyrolusite ore contains Mn (manganese).

Why other options are wrong:
- Option A: Fe is the main component of iron ores like hematite and magnetite.
- Option B: Al is the main component of aluminum ores like bauxite.
- Option D: Cu is the main component of copper ores like chalcopyrite and malachite.

Key Concepts:
- Pyrolusite Composition
- Manganese Ores

Memory Aids:
- Pyrolusite: $MnO_2$ (Manganese Dioxide)

Quick Tips:
- Memorize the chemical formulas of common ores.
- Know the main metal component of each ore.

48 Easy

48 of 69Question permalink

Remembering +4 | -1

The tempering of steel makes it:

View answer and explanation

Correct option: B

Soft

Option B (Soft) is correct because tempering steel reduces its brittleness and makes it softer and more ductile.

Solution approach

Correct Answer + Core Reason: Soft. Tempering makes steel less brittle and softer.

Step-by-Step Solution:

Step 1: Define tempering of steel.

Step 2: Tempering is a heat treatment process applied to steel after hardening to achieve greater toughness by reducing the hardness.

Step 3: Tempering reduces the brittleness and internal stresses in the steel.

Step 4: The process involves heating the hardened steel to a specific temperature below its critical temperature, holding it at that temperature for a period, and then cooling it.

Step 5: Conclude that tempering makes steel softer.

Why other options are wrong:
- Option A: Hard is incorrect. Tempering reduces hardness.
- Option C: Heavy is incorrect. Tempering does not significantly affect the weight of the steel.
- Option D: Brittle is incorrect. Tempering reduces brittleness.

Key Concepts:
- Tempering of steel.
- Heat treatment processes.
- Effects on hardness and brittleness.

Memory Aids:
- Tempering makes steel less "temperamental" (brittle).

Quick Tips:
- Remember that tempering follows hardening and aims to improve toughness.

49 Easy

49 of 69Question permalink

Remembering +4 | -1

In electrolytic purification, which of the following is made of impure metal?

View answer and explanation

Correct option: A

Anode

Option A (Anode) is correct because in electrolytic purification, the impure metal is used as the anode, where it gets oxidized and dissolved into the electrolyte.

Solution approach

Correct Answer + Core Reason: Anode. Impure metal is oxidized at the anode during electrolytic purification.

Step-by-Step Solution:

Step 1: Understand the process of electrolytic purification.

Step 2: Recall that the anode is where oxidation occurs, and the impure metal is oxidized and dissolved into the electrolyte.

Step 3: The cathode is where the pure metal is deposited.

Step 4: Therefore, the impure metal is made of the anode.

Why other options are wrong:
- Option B: Cathode is made of pure metal where metal ions get reduced and deposited.
- Option C: Both anode and cathode are not made of impure metal. Only anode is.
- Option D: Anode is made of impure metal.

Key Concepts:
- Electrolytic purification
- Oxidation and reduction
- Anode and cathode

Memory Aids:
- AN OX (Anode Oxidation)
- RED CAT (Reduction Cathode)

Quick Tips:
- Remember the roles of anode and cathode in electrolysis.

50 Easy

50 of 69Question permalink

Understanding +4 | -1

Carbon shows maximum capacity of catenation because:

View answer and explanation

Correct option: D

C—C bond strength is very high

Option D (C—C bond strength is very high) is correct because the high bond strength allows carbon atoms to form long chains and rings.

Solution approach

Correct Answer + Core Reason: C—C bond strength is very high. Carbon's ability to catenate depends on the high strength of C-C bonds.

Step-by-Step Solution:

Step 1: Define catenation. Catenation is the ability of an element to form bonds with itself, leading to chains or rings.

Step 2: Consider the factors affecting catenation. These include bond strength and the ability to form stable bonds with itself.

Step 3: Analyze carbon's properties. Carbon has a relatively small size and high electronegativity, leading to strong covalent bonds with itself.

Step 4: Compare carbon to other elements. While other elements can catenate, carbon does so to a much greater extent due to its strong C-C bond.

Why other options are wrong:
- Option A: Carbon shows variable valency. While carbon does exhibit variable valency, this is not the primary reason for its catenation ability. Variable valency allows it to form different types of compounds, but the strength of the C-C bond is what allows for long chains.
- Option B: In carbon there is one extra empty d-orbital. Carbon does not have accessible d-orbitals for bonding. It is a second-period element and only has s and p orbitals in its valence shell. The absence of d-orbitals does not directly contribute to catenation.
- Option C: C—C bond strength is very low. This is incorrect. A low bond strength would hinder catenation, not promote it. Elements with weak self-bonds do not catenate well.

Key Concepts:
- Catenation
- Bond Strength
- Electronegativity

Memory Aids:
- Catenation: \"Cat\"enation - think of a cat playing with a long chain.

Quick Tips:
- Remember that bond strength is crucial for catenation. The stronger the bond, the more stable the chain or ring.

51 Easy

51 of 69Question permalink

Remembering +4 | -1

The variety of iron having highest melting point is:

View answer and explanation

Correct option: C

Wrought iron

Option C is correct because Wrought iron has the highest melting point among the given options due to its low carbon content.

Solution approach

Correct Answer + Core Reason: Wrought iron. Wrought iron has the highest melting point due to its very low carbon content.

Step-by-Step Solution:

Step 1: Recall the different types of iron and their carbon content.

Step 2: The melting point of iron decreases with increasing carbon content.

Step 3: Compare the carbon content of the given options:
- Pig iron: Highest carbon content (3.5-4.5%)
- Cast iron: High carbon content (2-4%)
- Wrought iron: Very low carbon content (0.02-0.08%)
- Steel: Intermediate carbon content (0.25-2%)

Step 4: Since wrought iron has the lowest carbon content, it has the highest melting point.

Why other options are wrong:
- Option A: Pig iron has a high carbon content and a lower melting point.
- Option B: Cast iron has a high carbon content and a lower melting point.
- Option D: Steel has an intermediate carbon content and a lower melting point than wrought iron.

Key Concepts:
- Types of iron
- Carbon content and melting point

Memory Aids:
- Wrought iron is tough and has very little carbon.

Quick Tips:
- Remember that increasing carbon content lowers the melting point of iron.

52 Easy

52 of 69Question permalink

Understanding +4 | -1

Furnaces are lined with calcium oxide because:

View answer and explanation

Correct option: C

It is refractory and basic

Option C (It is refractory and basic) is correct because calcium oxide (CaO) is a refractory material (high melting point) and is basic in nature, making it suitable for lining furnaces, especially those used to process acidic ores.

Solution approach

Correct Answer + Core Reason: CaO is refractory and basic.

Step-by-Step Solution:

Step 1: Recall the properties of calcium oxide (CaO).

Step 2: CaO has a high melting point (refractory) and is basic in nature.

Step 3: Basic linings are used in furnaces to react with acidic impurities.

Why other options are wrong:
- Option A: CaO does not readily give off oxygen on heating.
- Option B: CaO does not primarily give off light on heating.
- Option D: CaO is affected by acids; it reacts with them.

Key Concepts:
- Refractory materials
- Basic oxides
- Furnace linings

Memory Aids:
- CaO is "strong" and "basic", good for furnace linings.

Quick Tips:
- Know the properties of common furnace lining materials.

53 Easy

53 of 69Question permalink

Understanding +4 | -1

Metal which can be extracted from all the three dolomite, magnesite and carnallite is

View answer and explanation

Correct option: C

Mg

Option C (Mg) is correct because Dolomite (

\mathrm{CaMg(CO}_3\mathrm{)}_2

), Magnesite (

\mathrm{MgCO}_3

), and Carnallite (

\mathrm{KCl.MgCl}_2.6\mathrm{H}_2\mathrm{O}

) all contain magnesium.

Solution approach

Correct Answer + Core Reason: Mg. Magnesium can be extracted from all three minerals.

Step-by-Step Solution:
Step 1: Identify the chemical formulas of the given minerals.
Step 2: Dolomite ( $\mathrm{CaMg(CO}_3\mathrm{)}_2$ ) contains magnesium.
Step 3: Magnesite ( $\mathrm{MgCO}_3$ ) contains magnesium.
Step 4: Carnallite ( $\mathrm{KCl.MgCl}_2.6\mathrm{H}_2\mathrm{O}$ ) contains magnesium.

Why other options are wrong:
- Option A: Na can be extracted from some minerals but not all three.
- Option B: K can be extracted from some minerals but not all three.
- Option D: Ca can be extracted from some minerals but not all three.

Key Concepts:
- Mineral composition
- Extraction of metals

Memory Aids:
- Remember the composition of common minerals.

Quick Tips:
- Analyze the chemical formulas of the minerals.

54 Easy

54 of 69Question permalink

Remembering +4 | -1

The purest zinc is made by

View answer and explanation

Correct option: B

Zone refining

Option B (Zone refining) is correct because Zone refining is a method used to obtain ultra-pure metals, including zinc.

Solution approach

Correct Answer + Core Reason: Zone refining. Zone refining is used to obtain the purest form of zinc.

Step-by-Step Solution:

Step 1: Define Zone Refining: Zone refining is a method used to purify solid materials, especially semiconductors, by repeatedly passing a narrow molten zone through the material. Impurities tend to concentrate in the molten zone.

Step 2: Consider Electrolytic Refining: Electrolytic refining is used for metals like copper, silver, and gold, but it doesn't achieve the same level of purity as zone refining.

Step 3: Consider Van-Arkel Method: The Van-Arkel method is used for refining metals like zirconium and titanium, which require very high purity.

Step 4: Consider Mond Process: The Mond process is specifically used for refining nickel.

Step 5: Zone refining is the most effective method for obtaining the highest purity in metals like zinc.

Why other options are wrong:
- Option A: Electrolytic refining is used for purification but doesn't yield the purest zinc compared to zone refining.
- Option C: The Van-Arkel method is used for metals like Zr and Ti, not Zn.
- Option D: The Mond process is specifically for nickel.

Key Concepts:
- Zone Refining
- Electrolytic Refining
- Van-Arkel Method
- Mond Process

Memory Aids:
- Zone Refining: Impurities move to the molten zone.

Quick Tips:
- Understand the principles behind each refining method.
- Know which metals are typically refined by each method.

55 Easy

55 of 69Question permalink

Understanding +4 | -1

Which of the following will show Tyndall effect

View answer and explanation

Correct option: B

Aqueous solution of soap above critical micelle concentration

Option B (Aqueous solution of soap above critical micelle concentration) is correct because Tyndall effect is exhibited by colloidal solutions, which form above the CMC.

Solution approach

Correct Answer + Core Reason: Aqueous solution of soap above critical micelle concentration. Tyndall effect is shown by colloidal solutions.

Step-by-Step Solution:

Step 1: Tyndall effect is the scattering of light by particles in a colloid or a fine suspension.

Step 2: For a soap solution, micelles are formed above the critical micelle concentration (CMC). These micelles are colloidal in nature.

Step 3: The colloidal particles scatter light, thus exhibiting the Tyndall effect.

Why other options are wrong:
- Option A: Below CMC, the soap solution is a true solution and does not exhibit the Tyndall effect.
- Option C: Aqueous solution of sodium chloride is a true solution and does not exhibit the Tyndall effect.
- Option D: Aqueous solution of sugar is a true solution and does not exhibit the Tyndall effect.

Key Concepts:
- Tyndall effect
- Colloids
- Critical Micelle Concentration (CMC)

Memory Aids:
- Tyndall effect is for colloids, micelles are colloids above CMC.

Quick Tips:
- True solutions do not show Tyndall effect, only colloids and suspensions do.

56 Easy

56 of 69Question permalink

Understanding +4 | -1

Which process is used for benefication of ores?

View answer and explanation

Correct option: A

Process of removal of impurities

Option A (Process of removal of impurities) is correct because beneficiation is the process of increasing the concentration of the desired ore by removing impurities.

Solution approach

Correct Answer + Core Reason: Process of removal of impurities. Beneficiation is the process of concentrating the ore by removing unwanted materials.

Step-by-Step Solution:

Step 1: Define beneficiation. Beneficiation refers to the processes that improve the economic value of ore by removing gangue (unwanted materials).

Step 2: Consider the purpose of beneficiation. The purpose is to increase the concentration of the desired mineral in the ore before further processing (e.g., smelting, leaching).

Step 3: Examples of beneficiation methods. These include gravity separation, magnetic separation, froth flotation, and leaching.

Why other options are wrong:
- Option B: Process of heating ore at high temperature. Heating ore at high temperature is typically part of smelting or roasting, not beneficiation. These processes are used to extract the metal from the concentrated ore.
- Option C: Extraction of metal from ore. Extraction of the metal is a separate step that follows beneficiation. Beneficiation prepares the ore for extraction.
- Option D: None of the above. Option A is the correct definition of beneficiation.

Key Concepts:
- Beneficiation
- Ore Concentration
- Gangue

Memory Aids:
- Beneficiation: \"Benefit\" - to improve the ore's value by removing impurities.

Quick Tips:
- Remember that beneficiation is a pre-treatment step to increase the concentration of the desired mineral.

57 Easy

57 of 69Question permalink

Understanding +4 | -1

Forth floatation process for the concentration of the ores is an illustration of the practical application of

View answer and explanation

Correct option: A

Adsorption

Option A (Adsorption) is correct because froth floatation relies on the adsorption of ore particles onto air bubbles.

Solution approach

Correct Answer + Core Reason: Forth floatation process is an illustration of adsorption.

Step-by-Step Solution:

Step 1: Froth floatation is a process used to separate valuable minerals from gangue (waste rock).

Step 2: The process involves creating a froth by bubbling air through a mixture of the ore, water, and surfactants (frothing agents).

Step 3: The valuable mineral particles are selectively adsorbed onto the air bubbles due to their hydrophobic nature or after being treated with collectors.

Step 4: The froth, containing the mineral particles, rises to the surface and is collected, separating it from the gangue.

Why other options are wrong:
- Option B: Sedimentation is the settling of particles, not the principle behind froth floatation.
- Option C: Coagulation is the clumping together of particles, not the primary mechanism in froth floatation.
- Option D: Absorption is the process of a substance dissolving into another, not the surface adhesion involved in froth floatation.

Key Concepts:
- Froth floatation
- Adsorption
- Surface chemistry

Memory Aids:
- Floatation = Adsorption on bubbles

Quick Tips:
- Remember that froth floatation relies on the selective adsorption of minerals onto air bubbles.

58 Easy

58 of 69Question permalink

Understanding +4 | -1

Metallic silver may be obtained from

\mathrm{AgCl}

by

View answer and explanation

Correct option: D

Fusing it with

\mathrm{N}{\mathrm{a}_2}\mathrm{C}{\mathrm{O}_3}

Option D (Fusing it with

\mathrm{N}{\mathrm{a}_2}\mathrm{C}{\mathrm{O}_3}

) is correct because fusing silver chloride with sodium carbonate reduces it to metallic silver.

Solution approach

Correct Answer + Core Reason: Fusing it with $\mathrm{N}{\mathrm{a}_2}\mathrm{C}{\mathrm{O}_3}$ . Fusing with sodium carbonate reduces AgCl to metallic silver.

Step-by-Step Solution:
Step 1: Consider the chemical reactions involved in obtaining metallic silver from AgCl.
Step 2: Fusing AgCl with $\mathrm{N}{\mathrm{a}_2}\mathrm{C}{\mathrm{O}_3}$ leads to the following reaction:
$2\mathrm{AgCl} + \mathrm{Na}_2\mathrm{CO}_3 \rightarrow 2\mathrm{Ag} + 2\mathrm{NaCl} + \mathrm{CO}_2 + \frac{1}{2}\mathrm{O}_2$

Why other options are wrong:
- Option A: Heating it in the current of ${\mathrm{H}_2}$ can reduce AgCl, but is less common than using sodium carbonate.
- Option B: Fusing it with sand (SiO2) will not reduce AgCl to metallic silver.
- Option C: Treating with carbon monoxide may reduce AgCl, but is less effective than using sodium carbonate.

Key Concepts:
- Reduction reactions
- Metallurgy of silver

Memory Aids:
- Sodium carbonate is a reducing agent.

Quick Tips:
- Remember common reducing agents.

59 Easy

59 of 69Question permalink

Understanding +4 | -1

Which represents calcination?

View answer and explanation

Correct option: D

\mathrm{MgC}{\mathrm{O}_3} \to \mathrm{MgO} + \mathrm{C}{\mathrm{O}_2}

Option D (

\mathrm{MgC}{\mathrm{O}_3} \to \mathrm{MgO} + \mathrm{C}{\mathrm{O}_2}

) is correct because calcination involves heating a carbonate ore in the absence of air to decompose it into its oxide.

Solution approach

Correct Answer + Core Reason: $\mathrm{MgC}{\mathrm{O}_3} \to \mathrm{MgO} + \mathrm{C}{\mathrm{O}_2}$ . Calcination is heating an ore, typically a carbonate, to decompose it.

Step-by-Step Solution:

Step 1: Identify the definition of calcination. Calcination involves heating a carbonate ore strongly in the absence or limited supply of air, causing it to decompose and release carbon dioxide, leaving behind the metal oxide.

Step 2: Examine the given options.

Step 3: Option A involves a reaction with HCl and oxygen, which is not calcination.

Step 4: Option B involves a reaction with oxygen, which is roasting.

Step 5: Option C involves a reaction with oxygen, which is roasting.

Step 6: Option D shows the decomposition of magnesium carbonate into magnesium oxide and carbon dioxide upon heating, which is calcination.

Why other options are wrong:
- Option A: This reaction involves the formation of silver chloride using hydrochloric acid and oxygen, which is not calcination.
- Option B: This reaction involves the direct combination of zinc with oxygen, which is a form of oxidation, specifically roasting, not calcination.
- Option C: This reaction involves the oxidation of zinc sulfide with oxygen, producing zinc oxide and sulfur dioxide, which is roasting, not calcination.

Key Concepts:
- Calcination: Heating a carbonate ore to decompose it in the absence of air.
- Roasting: Heating a sulfide ore in the presence of air to convert it to an oxide.

Memory Aids:
- Calcination: Think "Carbonate" and "CO2" release.
- Roasting: Think "Sulfide" and "Oxygen" reaction.

Quick Tips:
- Remember the key difference between calcination and roasting: calcination is done in the absence of air, while roasting is done in the presence of air.

60 Easy

60 of 69Question permalink

Understanding +4 | -1

Zone refining is based on the principle that

View answer and explanation

Correct option: B

Impurities are more soluble in molten metal than in solid metal

Option B (Impurities are more soluble in molten metal than in solid metal) is correct because zone refining relies on the principle that impurities prefer to stay in the liquid (molten) phase as the solid metal crystallizes.

Solution approach

Correct Answer + Core Reason: Impurities are more soluble in molten metal than in solid metal. This is the fundamental principle of zone refining.

Step-by-Step Solution:

Step 1: Zone refining involves passing a molten zone along a solid metal rod.

Step 2: Impurities tend to concentrate in the molten zone because they are more soluble in the liquid phase than in the solid phase.

Step 3: As the molten zone moves, it carries the impurities along with it, leaving behind a purer solid metal.

Why other options are wrong:
- Option A: Impurities of low boiling metals can be separated by distillation is the principle of distillation refining, not zone refining.
- Option C: Different components of a mixture are differently adsorbed on an adsorbent is the principle of chromatography.
- Option D: Vapours of volatile compound can be decomposed in pure metal is related to the Mond process for nickel refining.

Key Concepts:
- Zone refining
- Solubility
- Purification of metals

Memory Aids:
- Impurities prefer the molten zone.

Quick Tips:
- Zone refining is based on differential solubility.

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