101 previous year UPSC Prelims questions on 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.
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UPSC 2023Polity · Parliament
Q71. With reference to the Finance Bill and Money Bill in the Indian Parliament, consider the following statements: 1. When the Lok Sabha transmits the Finance Bill to the Rajya Sabha, it can amend or reject the Bill. 2. When the Lok Sabha transmits the Money Bill to the Rajya Sabha, it cannot amend or reject the Bill; it can only make recommendations. 3. In the case of disagreement between the Lok Sabha and the Rajya Sabha, there is no joint sitting for the Money Bill, but a joint sitting becomes necessary for the Finance Bill. How many of the above statements are correct?
Explanation
Statement 1 is incorrect: A Finance Bill (other than a Money Bill) is not solely a Money Bill, so the Rajya Sabha has the power to suggest amendments or reject it. However, If the finance bill is a money bill Rajyasabha has no power to amend or reject the bill.
Statement 2 is correct: As per Article 110, Rajya Sabha has no power to amend or reject a Money Bill. It can only make recommendations, which the Lok Sabha may accept or reject. If Rajya Sabha does not act within 14 days, the Money Bill is deemed to have been passed.
Statement 3 is correct: For the Money Bill, the Lok Sabha’s decision is final. So there is no question of deadlock. However, for a Finance Bill(other than Money Bill), in case of a disagreement, a joint sitting of both Houses may be called, as it is a normal Bill and not a Money Bill.
UPSC 2023Science and Technology · Miscellaneous
Q72. Consider the following actions: 1. Detection of car crash/collision, which result in the deployment of airbags almost instantaneously. 2. Detection of accidental free fall of a laptop towards the ground which results in the immediate turning off of the hard drive. 3. Detection of the tilt of the smartphone which results in the rotation of display between portrait and landscape mode. In how many of the above actions is the function of the accelerometer required?
Explanation
An accelerometer is an electromechanical device used to measure acceleration forces. These forces may be static like the continuous force of gravity or dynamic force to sense movement or vibrations.
Statement 1 is correct: Upon a collision, the crash sensor, typically an accelerometer, transmits a signal to the airbag control unit to deploy the airbags almost immediately.
Statement 2 is correct: Accelerometers in laptops protect hard drives from damage. If the laptop were to suddenly drop while in use, the accelerometer would detect the sudden free fall and immediately turn off the hard drive to avoid hitting the reading heads into the hard drive platter.
Statement 3 is correct: Accelerometer is used in smartphones as it detects the rotation of their display between portrait and landscape mode depending on the tilt of the phone.
UPSC 2023Science and Technology · Miscellaneous
Q73. 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
Q74. 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.
UPSC 2023Environment and Ecology · Protected Areas for the Biodiversity Conservation
Q75. Consider the following statements: Once the Central Government notifies an area as a ‘Community Reserve’. 1. The Chief Wildlife Warden of the State becomes the governing authority of such forest. 2. Hunting is not allowed in such areas. 3. People of such areas are allowed to collect non-timber forest produce. 4. People of such areas are allowed traditional agricultural practices. How many of the above statements are correct?
Explanation
Statement 1 is incorrect: The State Government will establish a Community Reserve management committee, which will be in charge of conserving, maintaining, and overseeing the community reserve in accordance with Section 36 D of the Wild-life Protection Act (WLPA). The committee will choose a chairman who will serve as the community reserve’s Honorary Wild Life Warden.
Statement 2 is correct: Community Reserves are designated to protect wildlife and biodiversity. Under the Wildlife Protection Act, 1972 hunting is strictly prohibited in all protected areas including Community Reserves. Section 9 of the Act prohibits hunting of wild animals listed in Schedules I, II, III, and IV.
Statement 3 is correct: In a Community Reserve, the collection of non-timber forest produce by the local communities is subject to the specific rules and regulations governing the Community Reserve. It may be regulated or restricted to ensure sustainable use and conservation of resources.
Statement 4 is incorrect: After a forest has been made into a community reserve, people cannot use it for agricultural practices, leave alone jhum cultivation.
UPSC 2023Environment and Ecology · Species
Q76. Invasive Species Specialist Group’ (that develops the Global Invasive Species Database) belongs to which one of the following organisations?
Explanation
The Invasive Species Specialist Group (ISSG) is a global network of scientific and policy experts on invasive species, organised under the auspices of the Species Survival Commission (SSC) of the International Union for Conservation of Nature (IUCN). The ISSG fosters and enables the worldwide exchange of knowledge and information concerning invasive species. It also ensures the linkage between knowledge, practice, and policy to ensure that decisions are based on well-informed insights.
UPSC 2023Environment and Ecology · Species
Q77. Consider the following statements: 1. Some mushrooms have medicinal properties. 2. Some mushrooms have psychoactive properties 3. Some mushrooms have insecticidal properties. 4. Some mushrooms have bioluminescent properties. How many of the above statements are correct?
Explanation
Statement 1 is correct: Mushrooms possess antibacterial properties, enhance the immune system, and aid in lowering cholesterol levels. Moreover, they serve as significant reservoirs of bioactive compounds. Consequently, certain mushroom extracts are utilised to support human health and are available in the form of dietary supplements.
Statement 2 is correct: Psychoactive properties refer to substances that influence brain function, resulting in alterations in mood, awareness, cognition, emotions, or behaviour. Psilocybin is a hallucinogenic compound found in specific mushrooms commonly known as magic mushrooms.
Statement 3 is correct: In recent times, there has been a growing discovery of insecticidal compounds within mushrooms.
Statement 4 is correct: Bioluminescence refers to the generation and release of light by living organisms. Panellus stipticus stands out as one of the most luminous bioluminescent mushrooms found on our planet. The newly discovered species, designated as Roridomyces phyllostachydis found in Meghalaya, now joins the ranks of the 97 recognised types of bioluminescent fungi world- wide.
Exam tip:
"Some" = possibility logic, not absolute. If even one species of organism does something, the statement is likely correct. UPSC uses "some" to lower the burden of proof harder to eliminate. Hence all statements are likely correct.
UPSC 2023Environment and Ecology · Species
Q78. Consider the following statements regarding the Indian squirrels: 1. They build nests by making burrows in the ground. 2. They store their food materials like nuts and seeds in the ground. 3. They are omnivorous. How many of the above statements are correct?
Explanation
Statement 1 is incorrect: Indian squirrels, such as the Indian Palm Squirrel, do not burrow in the ground to build nests. Instead, they construct nests in trees, crevices, or other elevated areas using materials like leaves and twigs. Burrow-making is more characteristic of rodents like rats or ground squirrels, which are not typical Indian squirrels.
Statement 2 is correct: Nuts serve as the primary food source for these creatures year-round, especially during the winter months when they are preparing for hibernation. They store nuts by burying them underground, enabling retrieval during the win-ter season.
Statement 3 is correct: Squirrels are omnivores. Their diet primarily consists of nuts and fruits, although they will also consume seeds, insects, small mammals, reptiles, eggs, and occasionally even bird chicks.
UPSC 2023Polity · Higher Judiciary: Supreme Court and High Courts
Q79. Consider the following statements: Statement-I: The Supreme Court of India has held in some judgments that the reservation policies made under Article 16(4) of the Constitution of India would be limited by Article 335 for the maintenance of efficiency of administration. Statement-II: Article 335 of the Constitution of India defines the term ‘efficiency of administration’. Which one of the following is correct in respect of the above statements?
Explanation
Statement 1 is correct: The Supreme Court of India has held in several judgments - Indra Sawhney v Union of India (1992) and M Nagaraj v Union of India (2006) that the reservation policies made under Article 16(4) of the Constitution would be limited by Article 335, which provides for ‘maintenance of efficiency of administration’, while considering the claims of the Scheduled Castes (SCs) and the Scheduled Tribes (STs) in the making of appointments to public services and posts.
Statement 2 is incorrect: Article 335 mentions that the claims of Scheduled Castes (SCs) and Scheduled Tribes (STs) must be considered in appointments to services and posts, but this must be consistent with the maintenance of efficiency in administration. However, Article 335 does not define the term "efficiency of administration", leaving its interpretation to judicial and administrative discretion. This gap in interpretation was filled by a two-judge bench in the B K Pavitra (II) v Union of India (2019), as it held that ‘efficiency of administration in the affairs of the union or of a state must be defined in an inclusive sense, where diverse segments of society find representation as a true aspiration of governance by and for the people’.
Exam tip:
For S2, The word "defines" is a strong and rigid claim. Think practically: The Constitution is not a dictionary. It doesn’t explicitly list out or define "efficiency of administration". Hence likely false. Gives option C as correct..
UPSC 2023Geography · Indian Geography
Q80. Consider the following trees: 1. Jackfruit (Artocarpus heterophyllus) 2. Mahua (Madhuca indica) 3. Teak (Tectona grandis) How many of the above are deciduous trees?
Explanation
Option 1 is incorrect: Jackfruit(Artocarpus heterophyllus) is an evergreen tree native to tropical regions of Asia. It retains its foliage throughout the year unlike deciduous trees, which shed their leaves during certain seasons. The tree thrives in hot and humid climates and is known for edible fruit that grows directly from the trunk. Jackfruit trees are common in India, Bangladesh, and Southeast Asia Option 2 is correct: Mahua (Madhuca indica) is a deciduous tree found in the dry forests of Central India including parts of Madhya Pradesh, Jharkhand, and Chhattisgarh. This tree sheds its leaves during the dry season to conserve water. Mahua is culturally significant in tribal communities and its flowers are used to make a traditional alcoholic drink. The tree’s flowers are also edible and have medicinal properties.
Option 3 is correct: Teak (Tectona grandis) is one of the most valuable hardwoods in the world. It is a deciduous tree that sheds its leaves in the dry season between February and March. It is known for its durability, resistance to weathering, and ability to withstand termites which makes it highly sought after for furniture, shipbuilding, and construction.
Answer key for these questions
Q
UPSC year
Correct answer
71
2023
(b) Only two
72
2023
(c) All three
73
2023
(b) Only two
74
2023
(c) All three
75
2023
(b) Only two
76
2023
(a) The International Union for Conservation of Nature
77
2023
(d) All four
78
2023
(b) Only two
79
2023
(c) Statement-I is correct but Statement-II is incorrect.
80
2023
(b) Only two
Frequently asked questions
How many previous year UPSC questions are there on all subjects?
This page covers 101 previous year UPSC Prelims GS Paper-I questions on the UPSC 2023 Prelims, asked from 1995 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 all subjects?
Questions on the UPSC 2023 Prelims are available for 31 years, from 1995 to 2025. Use the Year filter to practise a single paper.