41. Consider the following pairs:
| Transition Metal |
Notable Use |
| Scandium |
Aerospace alloys and high-intensity lamps |
| Titanium |
Biocompatible implants and white pigment (TiO₂) |
| Vanadium |
Steel alloys (strengthening agent) |
| Chromium |
Stainless steel and chrome plating |
How many of the above pairs are correctly matched?
[A] Only Three Pairs
[B] Only Two Pairs
[C] All Four Pairs
[D] Only One Pair
Show Answer
Correct Answer: C [All Four Pairs]
Notes:
All four pairs are correctly matched: Scandium is used in aerospace alloys and high-intensity lamps; Titanium in biocompatible implants and as a white pigment (TiO₂); Vanadium in steel alloys; Chromium in stainless steel and chrome plating.
42. Consider the following pairs:
| Fuel |
Well Known For |
| LPG |
Propane–butane mixture |
| Petrol |
High octane number |
| Diesel |
Low energy density |
How many of the above pairs are correctly matched?
[A] Only One Pair
[B] Only Two Pairs
[C] All Three Pairs
[D] None
Show Answer
Correct Answer: B [Only Two Pairs]
Notes:
LPG is a propane–butane mixture. Petrol is well known for its high octane number, and diesel for its high energy density.
43. Consider the following hydrocarbons:
- Ethyne
- Ethene
- Ethane
Which of the following correctly represents their order of increasing acidity?
[A] 1 < 2 < 3
[B] 2 < 3 < 1
[C] 2 < 1 < 3
[D] 3 < 2 < 1
Show Answer
Correct Answer: D [3 < 2 < 1]
Notes:
The acidity of hydrocarbons depends on the s-character of the hybridized carbon atom. Ethane (sp³; least acidic) < Ethene (sp²; moderate acidity) < Ethyne (sp; most acidic). Thus, the correct increasing order is: Ethane (3) < Ethene (2) < Ethyne (1), i.e., 3 < 2 < 1.
44. Consider the following statements:
- Methanol is poisonous and can cause blindness.
- Ethanol is used as an antiseptic in medical spirit.
- Hexane is a greenhouse gas more potent than methane.
Which of the above statements is / are correct?
[A] Only 1 and 2
[B] Only 2 and 3
[C] Only 1 and 3
[D] 1 and 2 only
Show Answer
Correct Answer: D [1 and 2 only]
Notes:
Methanol is toxic and ingestion can lead to blindness or death. Ethanol is commonly used as an antiseptic in spirit swabs and hand sanitizers. Hexane, however, is not classified as a greenhouse gas; methane is the potent greenhouse gas among hydrocarbons. Therefore, only statements 1 and 2 are correct.
45. Which of the following are produced by fermentation?
- Ethanol
- Citric acid
- Acetic acid
- Glucose
Select the correct answer using the codes given below:
[A] 1, 2, 3
[B] 1 and 4
[C] 2, 3, 4
[D] 1, 2, 3, 4
Show Answer
Correct Answer: A [1, 2, 3]
Notes:
Ethanol is obtained by yeast fermentation of sugars. Citric acid is industrially produced by fermentation using Aspergillus niger. Acetic acid is formed by bacterial oxidation of ethanol during fermentation. Glucose is not produced by fermentation; it is a monosaccharide primarily produced by plants during photosynthesis.
46. Consider the following pairs regarding plant source and their primary metabolite:
| Plant Source |
Metabolite |
| Opium poppy |
Morphine |
| Cinchona |
Nicotine |
| Coffee |
Quinine |
| Tobacco |
Caffeine |
How many of the pairs given above are correctly matched?
[A] Only One Pair
[B] Only Two Pairs
[C] Only Three Pairs
[D] All Four Pairs
Show Answer
Correct Answer: A [Only One Pair]
Notes:
Opium poppy yields morphine. Cinchona yields quinine, not nicotine. Coffee yields caffeine, not quinine. Tobacco yields nicotine, not caffeine. Only the first pair is correct.
47. Which of the following are condensation polymers?
- Polyethylene terephthalate (PET)
- Nylon
- Polyurethane
- Polyvinyl chloride (PVC)
Select the correct option from the codes given below:
[A] Only 1 and 2
[B] 1, 2 and 3
[C] Only 2 and 4
[D] 1, 2, 3 and 4
Show Answer
Correct Answer: B [1, 2 and 3]
Notes:
PET, Nylon, and Polyurethane are condensation polymers, formed by the elimination of small molecules like water during polymerization. Polyvinyl chloride (PVC) is an addition polymer produced from vinyl chloride monomers. Therefore, only options 1, 2, and 3 are condensation polymers, while PVC is not.
48. Which of the following are commonly used for heat-resistant kitchenware?
- Melamine-formaldehyde
- Urea-formaldehyde
- Polycarbonate
Select the correct answer using the codes given below:
[A] Only 1
[B] 1 and 2
[C] 1 and 3
[D] 2 and 3
Show Answer
Correct Answer: A [Only 1]
Notes:
Melamine-formaldehyde is heat-resistant and widely used in kitchenware due to its durability. Urea-formaldehyde is mainly used as an adhesive and is not typically used for kitchenware. Polycarbonate is heat-resistant and transparent but generally used for bottles and not common for kitchenware. Thus, only melamine-formaldehyde (1) is correct.
49. Which of the following daily processes are examples of endothermic changes?
- Melting of ice
- Cooking of food
- Respiration
- Photosynthesis
Select the correct option from the codes given below:
[A] 1, 2 & 4 only
[B] 2 & 3 only
[C] 1, 3 & 4 only
[D] 1, 2, 3 & 4
Show Answer
Correct Answer: A [1, 2 & 4 only]
Notes:
Endothermic changes absorb energy. Melting of ice absorbs heat, cooking of food requires energy input, and photosynthesis uses sunlight energy to synthesize organic compounds. Respiration is an exothermic process, releasing energy during glucose breakdown. Hence, only 1, 2, and 4 are endothermic processes among the options listed.
50. Consider the following applications of nuclear chemistry in medicine:
- X-rays are used for imaging bones and internal organs.
- Radioisotopes are used as tracers in diagnosing metabolic disorders.
- Gamma rays are employed in cancer therapy.
Which of the above statements is/are correct?
[A] Only 1
[B] 1 and 2 only
[C] 1, 2, and 3
[D] 2 and 3 only
Show Answer
Correct Answer: C [1, 2, and 3]
Notes:
All three statements are correct: X-rays are widely used for internal imaging; radioisotopes such as iodine-131 and technetium-99m serve as tracers for metabolic and organ function diagnostics; and gamma rays, due to their deep tissue penetration, are fundamental in cancer radiotherapy. Each is a significant application of nuclear chemistry in medicine.
