UPSC 2023 Science and Technology Questions with Answers
12 previous year UPSC Prelims questions on Science and Technology in the UPSC 2023 Prelims. Choose an option to see the answer and explanation.
Explanations state facts as of the year each question was asked; words like “recently” refer to that year.
Showing 11–12 of 12 questions
Browse Science and Technology chapters
UPSC 2023Science and Technology · Miscellaneous
Q11. With reference to the role of biofilters in Recircu-lating Aquaculture System, consider the following statements: 1. Biofilters provide waste treatment by removing uneaten fish feed. 2. Biofilters convert ammonia present in fish waste to nitrate. 3. Biofilters increase phosphorus as a nutrient for fish in water. How many of the statements given above are correct?
Explanation
Statement 1 is correct: The use of biofilters to remove toxins from wastewater and waste gases has advanced in recent decades. In order to remove contaminants from a fluid stream, biofilters fix microorganisms to an inorganic/organic medium (carrier), which has the ability to break down a wide range of chemicals. By removing uneaten fish feed, they additionally perform waste treatment.
Statement 2 is correct: By constructing a biofilter correctly, it is possible to regulate ammonia and nitrite concentrations at levels safe for fish. Through the biofiltration process, ammonia nitrogen is converted into nitrite nitrogen, which is subsequently transformed into less harmful nitrate nitrogen, ensuring a conducive environment for fish.
Statement 3 is incorrect: Biofilters do not increase phosphorus as a nutrient for fish in water. Phosphorus (P) is actually removed by biofilters to prevent eutrophication in waters.
UPSC 2023Science and Technology · Miscellaneous
Q12. With reference to green hydrogen, consider the following statements: 1. It can be used directly as a fuel for internal combustion. 2. It can be blended with natural gas and used as fuel for heat or power generation. 3. It can be used in the hydrogen fuel cell to run vehicles. How many of the above statements are correct?
Explanation
Green hydrogen is a renewable energy source that, unlike coal and oil, solely releases water vapour and leaves no residue in the air.
Statement 1 is correct: Hydrogen, a zero-carbon fuel, can be used to power automobiles through both hydrogen internal combustion engines and hydrogen fuel cells.Hydrogen engines utilize hydrogen in an internal combustion engine, operating similarly to the way gasoline powers conventional engines.
Statement 2 is correct: Clean hydrogen may be created and injected into natural gas pipelines to create blends that can be utilised to provide heat and power with fewer emissions than just natural gas.
Statement 3 is correct: A fuel cell harnesses the chemical energy of green hydrogen or alternative fuels to generate electricity in a clean and efficient manner. When hydrogen serves as the fuel, the sole byproducts produced are electricity, water, and heat.
Exam tip:
Again, "CAN" and "Some" = possibility logic, not absolute. If even one example exist, the statement is likely correct. UPSC uses "can" and "some" to lower the burden of proof harder to eliminate. Hence all statements are likely correct. Same logic in Question 155 also.
Answer key for these questions
Q
UPSC year
Correct answer
11
2023
(b) Only two
12
2023
(c) All three
Frequently asked questions
How many previous year UPSC questions are there on Science and Technology?
This page covers 12 previous year UPSC Prelims GS Paper-I questions on Science and Technology in the UPSC 2023 Prelims, asked from 1996 to 2025. Each has the correct answer and an explanation.
How should I use previous year UPSC questions for Prelims?
Attempt each question first, then open the answer and read the explanation for every option. Repeat by chapter, and track which statements UPSC reuses across years. Previous year questions show the exam pattern and difficulty level.
Which years are covered for Science and Technology?
Questions on Science and Technology in the UPSC 2023 Prelims are available for 30 years, from 1996 to 2025. Use the Year filter to practise a single paper.
