Science and Technology: UPSC Previous Year Questions (Prelims)

Explanation

India purchased the Barak anti-missile defence systems from Israel. The Barak system is developed by Israel Aerospace Industries (IAI) in collaboration with Rafael Advanced Defense Systems, is a surface-to-air missile designed to intercept and destroy incoming threats such as anti-ship missiles, aircraft, and drones. It is part of India’s naval defence system and is installed on various Indian Navy warships to enhance their anti-missile capabilities.

Explanation

5.5 ton class helicopter with twin engines. is an Advanced Light Helicopter (ALH) developed by Hindustan Aeronautics Limited (HAL) for military and civilian applications. Equipped with twin Shakti engines, it operates at altitudes up to 20,000 feet, making it suitable for diverse terrains. Dhruv is used for troop transport, search and rescue, reconnaissance, medical evacuation, and disaster relief. Its variants include the armed Rudra and the upgraded Mark III. As a symbol of India’s self-reliance in defense, Dhruv has been exported to countries like Nepal and Mauritius, enhancing India’s defense diplomacy.

Explanation

ITER, which stands for International Thermonuclear Experimental Reactor, is a massive international collaboration aimed at harnessing the power of nuclear fusion. This groundbreaking project is being constructed in Cadarache, Southern France. ITER aims to replicate nuclear fusion, where light atomic nuclei combine to release vast energy, offering a limitless, clean power source. Using a tokamak design, it employs powerful magnetic fields to heat plasma to over 150 million degrees Celsius. The project is a global collaboration involving China, the EU, India, Japan, Korea, Russia, and the US. India has provided in-wall shielding components and the cryo lines and cryo distribution system, crucial for the reactor’s operation.

Explanation

Statement 1 is correct: A jet engine relies on the oxygen in the Earth’s atmosphere for combustion. In space, where there is no atmosphere, a jet engine cannot function because it cannot obtain the necessary oxygen for burning fuel.

Statement 2 is incorrect: Rockets do carry their own supply of oxygen, but typically, the oxygen is not in gas form. It is usually stored as a liquid oxidizer (e.g., liquid oxygen, LOX) along with the fuel.

Explanation

Option (b) is correct: Rubies and sapphires are both varieties of the mineral corundum, which is chemically known as aluminium oxide (Al₂O₃). The difference between rubies and sapphires lies in the trace elements present in them. Rubies get their red color from the presence of trace amounts of chromium. Sapphires can come in various colors, but they are typically blue due to trace amounts of iron and titanium. Options (a), (c) and (d) are incorrect:

Silicon dioxide (SiO₂) is the chemical compound for quartz, Lead tetroxide (Pb₄O₆) is a compound containing lead and oxygen and Boron nitride (BN) is a compound of boron and nitrogen. All three are not related to rubies or sapphires.

Explanation

Option (c) is correct: Xenon: Approximately 0.0000087% of Earth’s atmosphere, known as "stranger gas" due to its unusual behavior among noble gases. Unlike other noble gases, xenon can form compounds with other elements, such as xenon fluorides. It is used in high-intensity discharge lamps and flash lamps for bright illumination, explored as an anesthetic agent and in imaging techniques for the brain, heart, and lungs, and utilized in ion propulsion systems for satellites, contributing to efficient space travel. Options (a), (b) and (d) are incorrect:

Argon (Ar): Approximately 0.934% of Earth’s atmosphere, used in welding to create an inert atmosphere, in incandescent and fluorescent light bulbs to protect filaments from oxidation, and has potential as a neuroprotectant in medical applications. Neon: Neon (Ne) makes up about 0.0018% of Earth’s atmosphere. It is known for its use in neon signs that emit a reddish-orange glow. Neon is also used in lasers with helium to create specific light wavelengths. It helps detect leaks by identifying trace gases and is used as a cryogenic material for preserving biological specimens. Nitrous Oxide: Nitrous Oxide (N₂O), also called laughing gas, is colorless, odorless, and non-flammable. It has anesthetic properties and is used for minor surgeries and dental procedures. In the culinary field, it is used in whipped cream dispensers. In racing, it enhances engine power by allowing more fuel to burn, improving performance.

Explanation

Bisphenol A (BPA) is an industrial chemical extensively used in the production of polycarbonate plastics and epoxy resins. Polycarbonate plastics made using BPA are commonly employed in the manufacture of reusable water bottles, food containers, and baby bottles due to their durability and lightweight properties. Epoxy resins containing BPA are used as coatings for the inside of food and beverage cans to prevent corrosion and contamination. However, BPA is a controversial substance because it can leach into food and beverages under high temperatures or prolonged storage. It is considered a potential endocrine disruptor that may interfere with hormonal activity, prompting regulatory bodies worldwide to evaluate its safety in food-related applications.

Explanation

Methane and air are responsible for mine explosions, often referred to as fire damp explosions. Methane (CH₄) is a flammable gas that accumulates in coal mines. When mixed with air in the presence of a spark, it can cause deadly explosions. Options (a), (b) and (d) are incorrect:

While Hydrogen and Oxygen are explosive, these gases are not significantly common in mining environments. Oxygen and Acetylene are used in welding, not relevant to mine explosions. Carbon Dioxide and Methane: Carbon dioxide is inert and cannot contribute to mine explosions.

Explanation

Methane (CH₄) is a potent greenhouse gas with a global warming potential over 25 times greater than carbon dioxide (CO₂) over a 100-year period. The primary sources of methane emissions can be categorized into natural and anthropogenic (human-caused) sources.

Option 1 is correct: Rice fields emit methane due to the anaerobic decomposition of organic matter in waterlogged conditions. This is a significant contributor to global methane emissions, particularly in rice-producing countries.

Option 2 is correct: Coal mining releases methane trapped within coal seams during the mining process. This is known as fugitive methane emissions and is a key source of industrial methane.

Option 3 is correct: Domestic animals, particularly ruminants like cattle and sheep, produce methane during enteric fermentation, a digestive process where microbes break down food in the stomach.

Option 4 is correct: Wetlands are natural sources of methane, produced through the anaerobic decomposition of organic material in water-saturated soils.

Explanation

Option (a) is incorrect: Passion flower plant is not an insectivorous plant. Passion flowers are flowering plants, typically known for their beautiful blooms and use in ornamental gardening.

Option (b) is correct: Pitcher plant is an insectivorous plant that derives nutrients by trapping and digesting insects. Its leaves are modified into pitcher-like structures containing digestive fluids. Insects are lured by the plant’s bright colors and nectar and are trapped when they fall into the pitcher. This adaptation helps the plant survive in nutrient-poor soils such as those lacking nitrogen.

Option (c) is incorrect: Night queen also known as Raat ki Rani, this is a type of flowering plant known for its fragrant flowers that bloom at night. It is not insectivorous.

Option (d) is incorrect: Flame of the forest is a flowering tree (also known as Butea monosperma), primarily used for its ornamental and medicinal properties, and is not an insectivorous plant.