Materials and Nanotechnology for UPSC: BPA, Triclosan, Carbon Fibre, Nanoparticles, Rare Earths and Critical Minerals
How UPSC Tests Materials and Chemistry
🎯 Exam priority: Tier-1/2. Materials questions ask what a substance is used for, what makes it hazardous and why a technology works. UPSC asked: mandatory labelling of pre-packaged food (2016); the pressure cooker, why water dissolves so many substances, bisphenol A and triclosan (2021); nanoparticles (2022); carbon fibres (2023); the explosives CL-20, HMX and LLM-105 (2025); and rare earth elements and critical minerals (2026, provisional key). Mains asked about the Nano Mission and why nanotechnology is key (2016), nanotechnology in health (2020), in agriculture (2025) and alternative freshwater technologies (2024).
Everyday Chemistry, Plastics and Explosives
Everyday chemistry and materials
Item | What to know | Exam fact |
Water | A polar (dipolar) molecule, so it dissolves ionic and polar substances well | Water dissolves more substances than any other liquid because it is dipolar (2021) |
Pressure cooker | Raising the pressure raises the boiling point of water | The cooking temperature depends on the weight of the lid (valve) and the area of the vent hole, not the flame temperature (2021) |
Bisphenol A (BPA) | A building block of polycarbonate plastics and epoxy resins; an endocrine disruptor of concern | BPA is a key component of polycarbonate, not of LDPE, PET or PVC (2021) |
Triclosan | An antibacterial and antifungal agent | Found in toiletries such as soaps and toothpaste; harmful on long exposure at high levels (2021) |
Carbon fibre | Very strong, light fibre of carbon atoms | Used in car and aircraft parts and can be recycled (2023: statement that it cannot be recycled is wrong) |
CL-20, HMX, LLM-105 | High-energy nitrogen-rich compounds | Explosives used in military weapons (2025) |
Food labels | FSSAI packaging rules | Pre-packaged food must show ingredients including additives, nutrition information and the vegetarian or non-vegetarian mark; medical recommendations on allergy risk are not mandatory (2016) |
Nanotechnology, Critical Minerals and Freshwater Technologies
Nanotechnology
Nanotechnology works with materials of about 1 to 100 nanometres, where properties such as strength, reactivity and colour change. It is a key technology of the 21st century because it cuts across health, energy, materials and agriculture. India's Nano Mission (from 2007, under the Department of Science and Technology) funds research, infrastructure, human resources and international collaboration (Mains 2016).
Nanoparticles occur in nature (volcanic ash, sea spray), so the claim that they exist only when humans make them is wrong. Metal oxides such as titanium dioxide and zinc oxide are used in cosmetics and sunscreens, and some nanoparticles from commercial products can harm human health and the environment (2022 PYQ: statements 2 and 3).
Health (Mains 2020): targeted drug delivery, imaging, diagnostics and antibacterial coatings. In 2025 CSIR-CDRI developed a double-shell magnetic nanoparticle system that delivers doxorubicin precisely to breast cancer cells while sparing healthy cells.
Agriculture (Mains 2025): nano-fertilisers such as nano-urea and nano-DAP are used in tiny quantities, cut nutrient runoff and ease logistics; nano-sensors and nano-formulated pesticides improve targeting. Concerns are cost, effect on yield over several seasons and environmental fate.
Rare earths and critical minerals
There are 17 rare earth elements (not 13). They are used in magnets, electronics, AI hardware, robotics and space technology. China, not India, dominates mining and processing (2026 PYQ, provisional key: statements 1 and 3 right).
The Economic Survey calls lithium, cobalt, nickel, copper and rare earths 'strategic chokepoints' of the energy transition. One gigawatt of solar needs about 18.5 tonnes of silver, 2,000 to 3,000 tonnes of polysilicon and 10,252 tonnes of aluminium; a 1 GW wind farm needs about 2,866 tonnes of copper.
The National Critical Mineral Mission (January 2025; ₹16,300 crore of expenditure and an expected ₹18,000 crore of PSU investment) covers exploration, recovery from tailings, recycling and overseas assets; GSI has 1,200 exploration projects to 2030-31 and a ₹1,500 crore scheme promotes recycling of e-waste and battery scrap (secondary sources). DAE released India's first certified reference material for rare-earth ores, which certifies 13 elements and is the fourth of its kind in the world.
Freshwater technologies (Mains 2024)
Technology | Merit | Demerit |
Desalination by reverse osmosis | Gives a drought-proof supply on coasts | Energy-hungry and produces brine that harms marine life |
Wastewater recycling and reuse | Cuts demand on freshwater and is local | Needs advanced treatment and public acceptance |
Rainwater harvesting and aquifer recharge | Cheap and decentralised | Seasonal and depends on rainfall and land |
Atmospheric water generation and fog harvesting | Works away from water sources | Low yield and high energy for the output |
How UPSC Could Ask This Next
Substance-to-use pairs: BPA, triclosan, phthalates, PFAS, Teflon, aerogel, graphene.
Hazards: endocrine disruptors, microplastics, nanoparticle risks.
Strategic materials: rare earths, lithium, cobalt, gallium and germanium, and the programmes that secure them.
Principles: why water is a solvent, how a pressure cooker or a thermos works.
Further Reading
NCERT Biology (Class 12) and Geography textbooks, the India State of Forest Report, the MoEFCC Annual Report, the Economic Survey and the official lists cited in this note — the primary sources behind every figure above.
Test Yourself: Practice Questions and PYQs
Twelve practice questions on everyday chemistry, nanotechnology and critical minerals, followed by the real UPSC Prelims questions and exact Mains questions.
Practice Questions
Q1. Water can dissolve more substances than any other liquid because
(a) it is dipolar in nature
(b) it is a good conductor of heat
(c) it is an oxide of hydrogen
(d) it has a high specific heat
Show answer
Answer: (a) — UPSC's 2021 key.
Q2. In a pressure cooker, the temperature at which food cooks depends mainly on
1. the area of the vent hole in the lid
2. the temperature of the flame
3. the weight of the lid
(a) 1, 2 and 3
(b) 1 and 2 only
(c) 1 and 3 only
(d) 2 and 3 only
Show answer
Answer: (c) — The pressure set by the valve sets the boiling point.
Q3. Bisphenol A is a key component in the manufacture of
(a) low-density polyethylene
(b) polycarbonate plastics
(c) polyvinyl chloride
(d) polyethylene terephthalate
Show answer
Answer: (b) — It is also used in epoxy resins.
Q4. Triclosan is most likely to be present in
(a) toiletries
(b) fruit-ripening substances
(c) reused plastic containers
(d) food preservatives
Show answer
Answer: (a) — UPSC's 2021 key.
Q5. Carbon fibres
1. are used in making components of automobiles and aircraft.
2. once used cannot be recycled.
(a) 1 only
(b) 2 only
(c) Neither 1 nor 2
(d) Both 1 and 2
Show answer
Answer: (a) — UPSC's 2023 key.
Q6. CL-20, HMX and LLM-105 are
(a) rocket propellants
(b) explosives used in military weapons
(c) fuels for cruise missiles
(d) refrigerant alternatives to HFCs
Show answer
Answer: (b) — UPSC's 2025 key.
Q7. Which one of the following statements about nanoparticles is NOT correct?
(a) They have dimensions of roughly 1 to 100 nanometres
(b) They exist only when made by humans
(c) Some nanoparticles from commercial products can be unsafe for humans
(d) Some metal-oxide nanoparticles are used in cosmetics
Show answer
Answer: (b) — Nanoparticles also occur in nature, for example in volcanic ash and sea spray (UPSC's 2022 key).
Q8. How many rare earth elements are there?
(a) 7
(b) 13
(c) 30
(d) 17
Show answer
Answer: (d) — UPSC's 2026 provisional key rejected the statement that there are 13.
Q9. Which of the following is mandatory on pre-packaged food labels under FSSAI rules?
1. List of ingredients including additives
2. Nutrition information
3. Vegetarian or non-vegetarian mark
(a) 1, 2 and 3
(b) 1 and 2 only
(c) 1 and 3 only
(d) 2 and 3 only
Show answer
Answer: (a) — Medical recommendations on allergic reactions are not mandatory.
Q10. The National Critical Mineral Mission was approved by the Union Cabinet in
(a) January 2025
(b) March 2019
(c) December 2021
(d) July 2023
Show answer
Answer: (a) — It had expenditure of ₹16,300 crore (secondary sources).
Q11. India's first certified reference material for rare-earth ores, released by DAE in 2025, certifies how many rare earth elements?
(a) Three
(b) Seventeen
(c) Seven
(d) Thirteen
Show answer
Answer: (d) — It is the first in India and fourth in the world.
Q12. A disadvantage of reverse osmosis desalination is that it
(a) gives no usable water
(b) cannot be used on coasts
(c) is energy-intensive and produces brine
(d) needs rainfall
Show answer
Answer: (c) — The brine can harm marine ecosystems.
UPSC Previous Year Questions (PYQs)
Real UPSC Prelims questions, checked against the official paper and answer key.
Q1. (2016) With reference to pre-packaged items in India, as per the Food Safety and Standards (Packaging and Labeling) Regulations, 2011, it is mandatory for the manufacturer to put information on which of the following?
1. List of ingredients including additives
2. Nutrition information
3. Recommendation, if any, made by the medical profession about the possibility of any allergic reactions
4. Vegetarian/non-vegetarian
Select the correct answer using the code given below.
(a) 2, 3 and 4
(b) 1, 2 and 3
(c) 1, 2 and 4
(d) 1 and 4 only
Show answer
Answer: (c) — Pre-packaged food must carry the list of ingredients including additives, nutrition information and the vegetarian or non-vegetarian mark. A recommendation about possible allergic reactions is not mandatory, so statements 1, 2 and 4.
Q2. (2021) In a pressure cooker, the temperature at which the food is cooked depends mainly upon which of the following?
1. Area of the hole in the lid
2. Temperature of the flame
3. Weight of the lid
Select the correct answer using the code given below.
(a) 1 and 3 only
(b) 1, 2 and 3
(c) 2 and 3 only
(d) 1 and 2 only
Show answer
Answer: (a) — A pressure cooker raises the boiling point of water by raising the pressure, and the pressure depends on the weight of the lid (the valve) and the area of the vent hole. Flame temperature only changes how fast it heats.
Q3. (2021) Water can dissolve more substances than any other liquid because
(a) it is a good conductor of heat
(b) it is an oxide of hydrogen
(c) it has high value of specific heat
(d) it is dipolar in nature
Show answer
Answer: (d) — Water molecules are polar, so water dissolves ionic and polar substances better than most liquids.
Q4. (2021) Bisphenol A (BPA), a cause of concern, is a structural/key component in the manufacture of which of the following kinds of plastics?
(a) Polyvinyl chloride
(b) Polycarbonate
(c) Polyethylene terephthalate
(d) Low-density polyethylene
Show answer
Answer: (b) — Bisphenol A is a building block of polycarbonate plastics (and epoxy resins).
Q5. (2021) Triclosan, considered harmful when exposed to high levels for a long time, is most likely present in which of the following?
(a) Toiletries
(b) Reused plastic containers
(c) Fruit-ripening substances
(d) Food preservatives
Show answer
Answer: (a) — Triclosan is an antibacterial agent found in toiletries such as soaps, toothpastes and deodorants.
Q6. (2022) Consider the following statements:
1. Other than those made by humans, nanoparticles do not exist in nature.
2. Nanoparticles of some metallic oxides are used in the manufacture of some cosmetics.
3. Nanoparticles of some commercial products which enter the environment are unsafe for humans.
Which of the statements given above is/are correct?
(a) 1 only
(b) 1 and 2 only
(c) 3 only
(d) 2 and 3 only
Show answer
Answer: (d) — Nanoparticles also occur in nature (volcanic ash, sea spray), so statement 1 is wrong. Metal oxides such as titanium dioxide and zinc oxide are used in cosmetics, and some nanoparticles from commercial products can harm people, so statements 2 and 3.
Q7. (2023) Consider the following statements:
1. Carbon fibres are used in the manufacture of components used in automobiles and aircrafts.
2. Carbon fibres once used cannot be recycled.
Which of the statements given above is/are correct?
(a) 2 only
(b) Both 1 and 2
(c) Neither 1 nor 2
(d) 1 only
Show answer
Answer: (d) — Carbon fibres are strong and light and are used in car and aircraft parts. They can be recycled, so statement 2 is wrong.
Q8. (2025) What is the common characteristic of the chemical substances generally known as CL-20, HMX and LLM-105, which are sometimes talked about in media?
(a) These are alternatives to hydrofluorocarbon refrigerants
(b) These are fuels for rocket propulsion
(c) These are high-energy fuels for cruise missiles
(d) These are explosives in military weapons
Show answer
Answer: (d) — CL-20, HMX and LLM-105 are high-energy explosives used in military weapons.
Q9. (2026, provisional key) Which of the following statements about Rare Earth Elements (REEs) and Critical Minerals is/are correct?
1. Modern technological innovations including Artificial Intelligence, robotics and space exploration extensively utilise Rare Earth Elements (REEs).
2. China has the highest share in mining of REEs followed by India.
3. The Government of India launched the National Critical Mineral Mission (NCMM) in 2025 to establish a robust framework for self-reliance in the critical mineral sector.
4. Rare Earth Elements are a set of 13 metallic elements.
Select the answer using the code given below :
(a) 1, 3 and 4
(b) 1, 2 and 4
(c) 1 and 3 only
(d) 3 only
Show answer
Answer: (c) — AI, robotics and space technology use rare earth elements, and India launched the National Critical Mineral Mission in 2025. China, not India, leads the mining of rare earths, and there are 17, not 13, rare earth elements. So statements 1 and 3.
Mains Practice Questions
Use these to frame full-length answers. You don't have to answer one exactly — they show the angles UPSC tests, so let them guide which points you cover.
Why is nanotechnology one of the key technologies of the 21st century? Describe the salient features of the Nano Mission and its scope in development.
What do you understand by nanotechnology and how is it helping in the health sector?
How does nanotechnology offer significant advancements in agriculture? How can it help to uplift the socio-economic status of farmers?
The world faces an acute shortage of clean and safe freshwater. Discuss any three alternative technologies with their merits and demerits.
Why are critical minerals described as the new strategic chokepoints? Assess India's National Critical Mineral Mission.
UPSC Mains — Previous Years’ Questions on this topic (last 10 years)
These are the actual GS Mains questions UPSC has asked on this theme — real proof of how, and when, it is tested. Try to write a full answer to each.
2025 (GS-III): How does nanotechnology offer significant advancements in the field of agriculture ? How can this technology help to uplift the socio-economic status of farmers?
2024 (GS-III): The world is facing an acute shortage of clean and safe freshwater. What are the alternative technologies which can solve this crisis? Briefly discuss any three such technologies citing their key merits and demerits.
2020 (GS-III): What do you understand by nanotechnology and how is it helping in health sector?
2016 (GS-III): Why is nanotechnology one of the key technologies of the 21st century? Describe the salient features of Indian Government's Mission on Nanoscience and Technology and the scope of its application in the development process of the country.