21. Which of the following are examples of secondary cells?
- Lead–acid battery
- Nickel–cadmium battery
- Zinc–carbon battery
- Lithium–ion battery
Select the correct option from the codes given below:
[A] 1, 2, and 4 only
[B] 1 and 3 only
[C] 2 and 3 only
[D] 1, 2, 3, and 4
Show Answer
Correct Answer: A [1, 2, and 4 only]
Notes:
Secondary cells are rechargeable electrochemical devices. Lead–acid, nickel–cadmium, and lithium–ion batteries are main types of secondary (rechargeable) cells. Zinc–carbon batteries are primary cells, which are non-rechargeable and single-use. Therefore, only options 1, 2, and 4 correctly represent secondary cells.
22. Consider the following statements:
- Sucrose is the sweetest of all naturally occurring carbohydrates
- Acetylene is the basic chemical building block of natural rubber
Which of the above statements is / are correct?
[A] Neither 1 nor 2
[B] Only 1
[C] Only 2
[D] Both 1 and 2
Show Answer
Correct Answer: A [Neither 1 nor 2]
Notes:
Sucrose is not the sweetest naturally occurring carbohydrate; fructose is sweeter than sucrose. Acetylene is not the primary chemical building block of natural rubber. Instead, natural rubber consists mainly of polyisoprene, which is derived from isoprene monomers obtained from latex, not acetylene.
23. Which of the following statements about Carbon Monoxide are correct:
- It gets produced by incomplete combustion of fossil fuels
- It has a foul smell
- It is one of the ozone-depleting substances
- It contributes significantly to the greenhouse effect
Select the correct option from the codes given below:
[A] Only 1
[B] Only 1 & 2
[C] Only 2, 3 & 4
[D] Only 1, 3 & 4
Show Answer
Correct Answer: A [Only 1]
Notes:
Statement 1 is correct as carbon monoxide is produced by incomplete combustion of fossil fuels. Statement 2 is incorrect; CO is colorless, tasteless and odorless. Statement 3 is incorrect; CO is not an ozone-depleting substance. Statement 4 is incorrect; CO is not considered a significant greenhouse gas since it does not trap heat in the atmosphere.
24. Consider the following statements regarding the presence of carbon monoxide in the atmosphere:
- It can enhance global warming indirectly by affecting the atmospheric composition.
- It can enhance the formation of ground-level ozone.
Which of the statements given above is / are correct?
[A] Only 1
[B] Only 2
[C] Both 1 and 2
[D] Neither 1 nor 2
Show Answer
Correct Answer: C [Both 1 and 2]
Notes:
Carbon monoxide (CO) is a weak greenhouse gas but indirectly enhances global warming by reacting with hydroxyl radicals, thereby increasing the atmospheric lifetime of stronger greenhouse gases like methane. Additionally, CO contributes to ground-level ozone formation as it participates in photochemical reactions in the troposphere. Hence, both statements 1 and 2 are correct.
25. Which of the following statements regarding magnetite ore of iron are correct:
- It is also known as black ore
- It contains 60% to 70% of pure iron
- It possesses magnetic properties
Select the correct option from the codes given below:
[A] Only 1
[B] Only 1 & 2
[C] Only 2 & 3
[D] 1, 2 & 3
Show Answer
Correct Answer: D [1, 2 & 3]
Notes:
Magnetite, also called black ore, is a significant source of iron. It contains about 60% to 70% pure iron, making it one of the richest iron ores. Magnetite exhibits strong magnetic properties, being the most magnetic among naturally occurring minerals. Therefore, all three statements are correct.
26. Consider the following pairs:
- Bauxite – Aluminium
- Siderite – Zinc
- Calamine – Iron
- Cassiterite – Tin
How many pairs given above are matched correctly?
[A] Only 1 pair
[B] Only 2 pairs
[C] Only 3 pairs
[D] Only 4 pairs
Show Answer
Correct Answer: B [Only 2 pairs]
Notes:
- Bauxiteis a naturally occurring, heterogeneous material composed primarily of one or more aluminium hydroxide minerals.
- Hematite, magnetite, limonite, siderite are the ores of iron.
- Zinc ore is most commonly found as zinc carbonate (ZnCO3), known as calamine or smithsonite.
- Cassiterite is an ore of tin.
27. Consider the following statements:
- Steel can easily be shaped, cut, or made into wire.
- Special alloys of steel can be made by adding small amounts of other metals such as aluminium, nickel, and copper.
Which of the above is / are correct?
[A] Only 1
[B] Only 2
[C] Both 1 and 2
[D] None of the above
Show Answer
Correct Answer: C [Both 1 and 2]
Notes:
Steel is tough and it can easily be shaped, cut, or made into wire. Special alloys of steel can be made by adding small amounts of other metals such as aluminium, nickel, and copper. Alloys give steel unusual hardness, toughness, or ability to resist rust.
28. Consider the following statements:
- Fluoride used to reduce cavities, comes from a mineral fluorite.
- Most toothpastes are made white with titanium oxide.
- The sparkle in some toothpastes comes from mica.
Which of the above is / are correct?
[A] Only 1 and 2
[B] Only 1 and 3
[C] Only 2 and 3
[D] All of the above
Show Answer
Correct Answer: D [All of the above ]
Notes:
In toothpaste, abrasive minerals like silica, limestone, aluminium oxide and various phosphate minerals do the cleaning. Fluoride which is used to reduce cavities, comes from a mineral-fluorite. Most toothpastes are made white with titanium oxide, which comes from minerals called rutile, ilmenite and anatase. The sparkle in some toothpastes comes from mica.
29. Consider the following statements:
- The term ore refers to an accumulation of any mineral mixed with other elements.
- For a mineral accumulation to be considered as an ore, its mineral content must be present in sufficient concentration to permit commercially viable extraction.
Which of the above statements is / are correct?
[A] Both 1 and 2
[B] Only 1
[C] Only 2
[D] None of the above
Show Answer
Correct Answer: A [Both 1 and 2]
Notes:
Ore is defined as an accumulation of a mineral mixed with other elements, and for it to qualify as ore, the mineral content must be present in concentrations sufficient to make extraction profitable. Thus, both statements accurately reflect the definition and commercial criteria for ores.
30. Consider the following statements:
- The common salt, magnesium and bromine are largely derived from ocean waters.
- The ocean beds lack manganese nodules.
Which of the above is / are correct?
[A] Only 1
[B] Only 2
[C] Both 1 and 2
[D] None of the above
Show Answer
Correct Answer: A [Only 1]
Notes:
The ocean waters contain vast quantities of minerals, but most of these are too widely diffused to be of economic significance. However, common salt, magnesium and bromine are largely derived from ocean waters. The ocean beds, too, are rich in manganese nodules.
