Miscellaneous: UPSC Previous Year Questions (Science and Technology)
68 previous year UPSC Prelims questions on applied science and technology appear here, from 2011 to 2025. This is the second-largest chapter and groups energy, vehicles, materials and everyday technology. The 2025 paper asked about alternative powertrain vehicles, EV battery elements, coal gasification and rare earth elements. The explanations name the technology and its use.
Explanations state facts as of the year each question was asked; words like “recently” refer to that year.
Showing 61–68 of 68 questions
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UPSC 2011Science and Technology · Miscellaneous
Q61. What is the difference between a CFL and an LED lamp? 1. To produce light, a CFL uses mercury vapour and phosphor while an LED lamp uses semiconductor material. 2. The average lifespan of a CFL is much longer than that of an LED lamp. 3. A CFL is less energy-efficient as compared to an LED lamp. Which of the statements given above is/are correct?
Explanation
Statement 1 is correct: An LED is a type of semiconductor light source with two leads. It is a p-n junction diode, which when turned on emits light. A fluorescent lamp is a low-pressure mercury-vapour gas-discharge light. In a CFL, an electric current is driven through a tube containing argon and a small amount of mercury vapor. This generates invisible ultraviolet light that excites a fluorescent coating (called phosphor) on the inside of the tube, which then emits visible light.
Statement 2 is incorrect: LED bulbs are much more efficient than CFL bulbs in terms of power consumption and life years.
Statement 3 is correct: LED bulbs consume less power as compared to CFL. LED bulbs are expensive as compared to CFL bulbs. LED bulbs are much more efficient than CFL bulbs.
UPSC 2011Science and Technology · Miscellaneous
Q62. Aspartame is an artificial sweetener sold in the market. It consists of amino acids and provides calories like other amino acids. Yet, it is used as a low-calorie sweetening agent in food items. What is the basis of this use?
Explanation
Aspartame is a non-saccharide artificial sweetener approximately 200 times sweeter than sucrose, and is commonly used as a substitute of sugar in foods and beverages. The commercial names for it are NutraSweet, Equal, and Canderel. It is a methyl ester of the aspartic acid / phenylalanine dipeptide. Since Aspartame is several times sweeter than table sugar, hence food items made with small quantities of aspartame yield fewer calories on oxidation.
UPSC 2011Science and Technology · Miscellaneous
Q63. Recently, "oilzapper" was in the news. What is it?
Explanation
Oilzapper is an eco-friendly technology for oil sludges and oil spills remediation. Oilzapping is the new technique using bacteria to get rid of oil spills. It is a bioremediation technique that involves the use of oil zapping bacteria. In essence, Oilzapper is a concoction of five distinct bacterial strains that have been immobilised and combined with a carrier substance (powdered corn cob). The Oilzapper consumes the hydrocarbon molecules found in crude oil and oily sludge, a dangerous hydrocarbon waste product produced by oil refineries, and transforms them into harmless CO₂ and water. This is exactly what its witty name implies.
UPSC 2011Science and Technology · Miscellaneous
Q64. A married couple adopted a male child. A few years later, twin boys were born to them. The blood group of the couple is AB positive and O negative. The blood group of the three sons is A positive, B positive, and O positive. The blood group of the adopted son is
Explanation
The blood group of the couple is AB Positive and O Negative. So their biological sons will have either blood group A or B. Thus we can infer that the blood group of the adopted son will be O.
UPSC 2011Science and Technology · Miscellaneous
Q65. A new optical disc format known as the Blu-ray Disc (BD) is becoming popular. In what way is it different from the traditional DVD? 1. DVD supports Standard Definition video while BD supports High Definition Video. 2. Compared to a DVD, the BD format has several times more storage capacity. 3. The thickness of BD is 2.4 mm while that of DVD is 1.2 mm. Which of the statements given above is/are correct?
Explanation
Statement 1 is correct: DVD stands for "Digital Versatile Disk" or "Digital Video Disc". It is a type of digital optical disc storage that can hold any kind of digital data but is frequently used to store pictures, audio, and video in standard definition. Blu-ray Disc is a digital disc storage format similar to CD and DVD, that is designed to record and play a large amount of data with high-definition quality.
Statement 2 is correct: Blu-ray Disc media include these features: 50GB capacity - Each disc can hold more than 10 standard DVDs.
Statement 3 is incorrect: The size of the Blu-ray disc is 120 millimetres in diameter with 1.2 millimetres thickness, which is the same as the size of a CD and DVD.
UPSC 2011Science and Technology · Miscellaneous
Q66. When the bark of a tree is removed in a circular fashion all around near its base, it gradually dries up and dies because:
Explanation
The tissue just beneath the bark called the phloem layer is in charge of moving food produced by photosynthesis from the leaves to the roots. This process is called girdling, and it is fatal to trees because it disrupts the transport of nutrients. Without this nourishment, the roots eventually perish and stop supplying the leaves with water and nutrients. Later, the leaves wither. Because its roots are starved of vitality, a tree that has had its bark removed in a circular pattern all around near its base gradually dries up and dies.
UPSC 2011Science and Technology · Miscellaneous
Q67. A layer in the Earth’s atmosphere called Ionosphere facilitates radio communication. Why? 1. The presence of ozone causes the reflection of radio waves to Earth. 2. Radio waves have a very long wavelength. Which of the statements given above is/are correct?
Explanation
Statement 1 is incorrect: The presence of ions, and not ozone, in the Ionosphere is responsible for radio communication. Ozone is primarily present in the Stratosphere and not in the Ionosphere.
Statement 2 is incorrect: They have frequencies from 300 GHz to as low as 3 kHz and corresponding wavelengths from 1 millimetre to 100 kilometres. They have a long range of wavelengths, so they can have very small wavelengths as well.
UPSC 2011Science and Technology · Miscellaneous
Q68. A genetically engineered form of brinjal, known as the Bt-brinjal, has been developed. The objective of this is:
Explanation
Bt Brinjal is the first Genetically Modified food crop in India that has reached the approval stage for commercialization. Bt Brinjal is a genetically modified (GM) crop created by inserting Cry1Ac gene from the soil bacterium Bacillus thuringiensis into Brinjal. Brinjal plants now have resistance to lepidopteran pests such the Brinjal Fruit and Shoot Borer (Leucinodes orbonalis) and Fruit Borer as a result of the gene’s insertion (Helicoverpa armigera).
Answer key for these questions
Q
UPSC year
Correct answer
61
2011
(c) 1 and 3 only
62
2011
(d) Aspartame is several times sweeter than table sugar, hence food items made with small quantities of aspartame yield fewer calories on oxidation.
63
2011
(a) It is an eco-friendly technology for the remediation of oily sludge and oil spills
64
2011
(a) O positive
65
2011
(b) 1 and 2 only
66
2011
(b) Roots are starved of energy
67
2011
(d) Neither 1 nor 2
68
2011
(a) To make it pest-resistant
What UPSC has tested in Miscellaneous
Full battery electric vehicles, hydrogen fuel cell vehicles and fuel cell hybrids are all alternative powertrain vehicles.
The exhaust of a Fuel Cell Electric Vehicle is water vapour.
Cobalt, lithium and nickel form battery cathodes; graphite is used in the anode.
Pumped-storage hydropower is discussed as a long-duration energy storage option.
Rare earth elements are used in flat televisions and other electronics.
Frequently asked questions
How many previous year UPSC questions are there on Miscellaneous?
This page covers 68 previous year UPSC Prelims GS Paper-I questions on Miscellaneous (Science and Technology), asked from 2011 to 2025. Each has the correct answer and an explanation.
What does a hydrogen fuel cell vehicle emit?
Only water vapour. A fuel cell combines hydrogen with oxygen from the air to produce electricity, with water as the by-product, so the vehicle has no tailpipe carbon emissions.
Which elements form the cathode of an EV battery?
In lithium-ion batteries, the cathode contains lithium combined with cobalt, nickel, manganese or iron phosphate depending on chemistry. Graphite, by contrast, is used in the anode, not the cathode.
What is pumped-storage hydropower?
A way of storing energy by pumping water to a higher reservoir when electricity is cheap and releasing it through turbines when demand is high. It is used as long-duration storage that balances solar and wind power.
