5 real UPSC Prelims PYQs, fully explained
Sampled from our question bank across 5 different years and subjects. Each question shows the correct answer, a brief explanation, and a detailed breakdown — exactly the way you'll find them inside the full craqdIAS practice experience.
I. Cobalt
II. Graphite
III. Lithium
IV. Nickel
How many of the above usually make up battery cathodes?
Pick an option to check your answer and see the explanation.
In typical Lithium-ion batteries used in electric vehicles, the cathode is made of lithium metal oxides. Common formulations include Lithium Cobalt Oxide (LCO), Nickel-Manganese-Cobalt (NMC), and Nickel-Cobalt-Aluminum (NCA). Therefore, Lithium, Cobalt, and Nickel are essential cathode materials. Graphite, on the other hand, is the primary material used for the anode. Thus, only three of the listed elements are used in cathodes.
The question requires identifying how many of the given elements are typically used in the cathode of electric vehicle (EV) batteries. The dominant battery technology for EVs is the Lithium-ion (Li-ion) battery.
A Li-ion battery consists of three primary components:
- Anode (Negative Electrode): Releases lithium ions into the electrolyte during discharge.
- Cathode (Positive Electrode): Accepts lithium ions from the electrolyte during discharge.
- Electrolyte: A medium that allows the flow of ions between the anode and cathode.
Let's analyze the role of each element mentioned:
- I. Cobalt (Co): Cobalt is a critical component in many high-performance cathodes. It provides structural stability, which enhances the battery's lifespan and safety. Common cathode chemistries like Lithium Cobalt Oxide (LCO), Nickel-Manganese-Cobalt (NMC), and Nickel-Cobalt-Aluminum (NCA) all use cobalt.
- II. Graphite (C): Graphite is the most widely used material for the anode, not the cathode. Its layered structure allows it to absorb and release lithium ions efficiently during the charge and discharge cycles (a process called intercalation).
- III. Lithium (Li): Lithium is the core charge carrier in the battery. The entire technology is based on the movement of lithium ions. The cathode itself is a lithium compound, typically a lithium metal oxide (e.g., LiCoO₂, LiNiMnCoO₂).
- IV. Nickel (Ni): Nickel is a key ingredient in modern high-energy-density cathodes. Increasing the proportion of nickel in chemistries like NMC and NCA increases the battery's specific energy, which allows for a longer driving range in EVs.
Based on this analysis, Lithium, Cobalt, and Nickel are all commonly used in the cathode materials of EV batteries. Graphite is used in the anode. Therefore, three out of the four listed elements are used in cathodes.
Hence, the correct option is C, as it correctly identifies that three of the elements are used in battery cathodes.
1. There are no parables in Upanishads.
2. Upanishads were composed earlier than the Puranas.
Which of the statements given above is/are correct ?
Pick an option to check your answer and see the explanation.
Statement 1 is incorrect as the Upanishads contain numerous parables and allegorical stories to explain complex philosophical ideas, such as the dialogue between Nachiketa and Yama in the Katha Upanishad. Statement 2 is correct because the Upanishads are part of the later Vedic literature (c. 800-500 BCE), whereas the Puranas were compiled much later, primarily during the Gupta and post-Gupta periods (c. 3rd century CE onwards).
The question requires an analysis of two statements concerning ancient Indian religious and philosophical texts: the Upanishads and the Puranas.
- Statement 1: There are no parables in Upanishads.
This statement is incorrect. The Upanishads, which are philosophical treatises, frequently use dialogues, allegories, and parables (didactic stories) to explain abstract metaphysical concepts. A prominent example is the Katha Upanishad, which presents its entire philosophy through the story and dialogue between a young boy, Nachiketa, and Yama, the god of death. Another example is in the Chandogya Upanishad, where the sage Uddalaka Aruni uses various analogies and stories to teach his son, Shvetaketu, about the nature of reality and the self (Atman), culminating in the famous dictum 'Tat Tvam Asi' (That Thou Art). The absolute claim that there are 'no' parables is factually wrong. - Statement 2: Upanishads were composed earlier than the Puranas.
This statement is correct. There is a clear chronological distinction between these two bodies of literature. The Upanishads form the concluding part of the Vedas (and are hence called Vedanta) and are considered part of the later Vedic corpus. Their composition is generally dated by scholars to the period between 800 BCE and 500 BCE. The Puranas, on the other hand, belong to the Smriti literature. While they contain material from ancient oral traditions, their compilation and composition in their present form are dated much later, primarily during the Gupta period (c. 3rd to 5th centuries CE) and continuing into the subsequent centuries.
Since Statement 1 is incorrect and Statement 2 is correct, the correct option is B.
Pick an option to check your answer and see the explanation.
The Charter Act of 1833 was the final step towards the centralization of administration in British India. It designated the Governor General of Bengal as the Governor General of India, vesting in him all civil and military powers. Consequently, Lord William Bentinck became the first Governor General of India.
The question asks to identify the specific British parliamentary act that changed the title of the head of the British administration in India from 'Governor General of Bengal' to 'Governor General of India'. This change signified a major step in the consolidation and centralization of British power.
- The Charter Act of 1833: This Act is the correct answer. It was a landmark piece of legislation that significantly altered the governance structure of British India. Its key provision in this context was the re-designation of the Governor General of Bengal as the Governor General of India. This act vested all civil and military authority for the entire territory of British India in this single office. Lord William Bentinck, who was the Governor General of Bengal at the time, became the first Governor General of India. The act also deprived the governors of Bombay and Madras of their legislative powers, further centralizing authority.
- The Regulating Act, 1773: This option is incorrect. This Act created the post of 'Governor General of Bengal' (not India) and established a council to assist him. It made the presidencies of Bombay and Madras subordinate to the Bengal presidency in certain matters, but it did not create an all-India head. Warren Hastings was the first Governor General of Bengal.
- The Pitt's India Act, 1784: This option is incorrect. This Act established a system of dual control by creating the Board of Control to manage political affairs, while the Court of Directors managed commercial affairs. It did not change the designation of the Governor General of Bengal.
- The Charter Act of 1793: This option is incorrect. This Act extended the East India Company's charter for another 20 years and made minor administrative adjustments. It did not alter the title of the Governor General.
Therefore, the Charter Act of 1833 was the specific legislation that elevated the post to represent authority over all of British India, reflecting the expanding and increasingly centralized nature of British rule.
Consider the following pairs :
| Reservoirs | States |
|---|---|
| 1. Ghataprabha | Telangana |
| 2. Gandhi Sagar | Madhya Pradesh |
| 3. Indira Sagar | Andhra Pradesh |
| 4. Maithon | Chhattisgarh |
How many pairs given above are not correctly
matched?
Pick an option to check your answer and see the explanation.
Out of the four pairs, only one is correctly matched. The Gandhi Sagar reservoir is in Madhya Pradesh. The other three are incorrect: Ghataprabha reservoir is in Karnataka, Indira Sagar reservoir is also in Madhya Pradesh, and Maithon reservoir is in Jharkhand. Therefore, a total of three pairs are not correctly matched.
The question requires identifying the number of incorrectly matched pairs of reservoirs and their corresponding states. Let's analyze each pair:
- Pair 1: Ghataprabha - Telangana
This pair is incorrectly matched. The Ghataprabha reservoir, also known as the Hidkal Dam, is located on the Ghataprabha River (a right-bank tributary of the Krishna River) in the Belagavi district of Karnataka.
- Pair 2: Gandhi Sagar - Madhya Pradesh
This pair is correctly matched. The Gandhi Sagar Dam is one of the four major dams built on the Chambal River. It is situated in the Mandsaur and Neemuch districts of Madhya Pradesh. It is a key component of the Chambal Valley Project.
- Pair 3: Indira Sagar - Andhra Pradesh
This pair is incorrectly matched. The Indira Sagar Dam is a major multipurpose project on the Narmada River, located in the Khandwa district of Madhya Pradesh. It is not in Andhra Pradesh.
- Pair 4: Maithon - Chhattisgarh
This pair is incorrectly matched. The Maithon Dam is located on the Barakar River and is a part of the Damodar Valley Corporation (DVC). It is situated in the state of Jharkhand, near the border with West Bengal, not in Chhattisgarh.
Based on the analysis, pairs 1, 3, and 4 are incorrectly matched. Thus, there are a total of three incorrectly matched pairs, making option C the correct answer.
- Brakes of motor vehicles
- Engines of motor vehicles
- Microwave stoves within homes
- Power plants
- Telephone lines
Select the correct answer using the code given below.
Pick an option to check your answer and see the explanation.
Magnetite particles are generated as pollutants primarily from high-temperature processes like combustion and friction. Major anthropogenic sources include brakes of motor vehicles (from friction) and engines of motor vehicles (from fuel combustion). Industrial sources like coal-fired power plants also release magnetite in their fly ash emissions. Microwave stoves and telephone lines are not recognized as significant sources for generating these specific pollutants.
The question asks to identify the sources of magnetite particles, which are environmental pollutants linked to neurodegenerative diseases. Magnetite (Fe₃O₄) is a naturally occurring iron oxide, but its ultrafine, nanoparticle form generated by human activities is of particular concern.
- Statement 1: Brakes of motor vehicles - This is a correct source. The braking process involves intense friction between brake pads and discs, generating high temperatures. This leads to the aerosolization of fine and ultrafine particles, a significant portion of which are iron oxides, including magnetite. This is a major component of non-exhaust traffic-related air pollution.
- Statement 2: Engines of motor vehicles - This is also a correct source. The combustion of fuel in internal combustion engines is an incomplete process that produces a variety of pollutants, including particulate matter (PM). These exhaust particles contain not only soot but also metallic compounds from fuel, additives, and engine wear. Studies have confirmed the presence of magnetite nanoparticles in vehicle exhaust.
- Statement 4: Power plants - This is a correct source. Coal-fired power plants are a major industrial source of magnetite pollution. Coal contains various minerals, and during high-temperature combustion, iron-containing minerals are converted into spherical magnetite particles, which are then released into the atmosphere as part of fly ash.
- Statement 3: Microwave stoves within homes - This is an incorrect source. Microwave ovens operate by using non-ionizing radiation to heat food. They do not involve combustion or any high-friction mechanical process that would generate and release magnetite particles as an environmental pollutant. While indoor cooking can be a source of particulate matter, the appliance itself is not a source of magnetite.
- Statement 5: Telephone lines - This is an incorrect source. Telephone lines are passive infrastructure, typically made of copper or fiber-optic cables with plastic insulation. They do not have any operational mechanism that generates pollutants. They may accumulate dust from the environment but are not a primary source.
Therefore, the correct sources listed are brakes of motor vehicles, engines of motor vehicles, and power plants.
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