Science & Technology Mixed Quiz: Set 32

The correct answer is B, hydrogen. A single proton, the nucleus of ordinary hydrogen, has a spin and therefore a magnetic moment, and hydrogen is by far the most abundant such nucleus in the body because the body is largely water and fat. This abundance, combined with a strong magnetic response, is why routine MRI is in effect proton imaging.

Option A, carbon, is abundant in the body but its common isotope carbon-12 has no net nuclear spin and gives no signal; only the rare carbon-13 is magnetically active, and it is used in research spectroscopy. Option C, sodium, and option D, phosphorus, do have magnetically active nuclei, and sodium-23 and phosphorus-31 imaging and spectroscopy exist in specialised research work, but their concentration in tissue is far too low for ordinary clinical scanning. Remember the chain: hydrogen proton, strong static field, radiofrequency pulse, relaxation signal, image.

The correct answer is B, Battery Electric Vehicle. A BEV carries no engine at all; it runs entirely on a traction battery that is charged from an external electricity supply, and it has no tailpipe emissions. The other three abbreviations in the same family are HEV for a hybrid electric vehicle, which has an engine and a small battery but no plug, PHEV for a plug-in hybrid, and FCEV for a fuel cell electric vehicle running on hydrogen.

Option A is an invented expansion, as is option D; a bi-fuel vehicle is one that can run on two fuels such as petrol and compressed natural gas, which is a different idea altogether and not an electric vehicle. Option C is wrong, though the word Bharat does appear in Indian charging standards such as Bharat AC-001 and Bharat DC-001. Learn the four categories as a set, because questions frequently describe one of them and ask you to name it.

The correct answer is B, lithium iron phosphate. LFP cells are prized for safety, long cycle life and the absence of cobalt, which makes them cheaper and less exposed to supply disruption; their weakness is a lower energy density, so a pack of the same range weighs more. They are widely used in buses, two and three wheelers and standard-range cars.

Option A is a plausible-sounding invention. Option C has nothing to do with batteries and belongs to rocketry. Option D is also invented. The chemistry to contrast with LFP is NMC, nickel manganese cobalt oxide, which packs more energy into the same weight and so gives longer range, at the cost of more expensive metals, more heat and greater dependence on cobalt from a small number of countries. Examiners like a direct comparison question between the two, usually on safety against energy density.

The correct answer is C, Both 1 and 2. LiFi (Light Fidelity) sends data wirelessly by switching LED light on and off far too fast for the eye to notice, and it can be many times faster than WiFi.

The idea was popularised by Professor Harald Haas of the University of Edinburgh in 2011. A LiFi bulb flickers at very high frequency, and a photodetector reads these changes as binary data. Because visible light has a far wider spectrum than the radio waves used by WiFi, laboratory tests have reached speeds many times higher than WiFi. Light cannot pass through walls, which limits range but makes the signal harder to intercept and free of radio interference, useful in hospitals and aircraft.

A is wrong because statement 2 is also correct.

B is wrong because statement 1, the use of light, is the very basis of LiFi.

D is wrong because both statements describe LiFi correctly.

Exam tip: WiFi uses radio waves; LiFi uses visible light from LEDs and cannot pass through walls.

The correct answer is B, tesla. The tesla is the SI unit of magnetic flux density, and clinical MRI scanners commonly work at one and a half or three tesla, produced by a superconducting coil kept cold by liquid helium. For comparison, the earth's own magnetic field is of the order of a few tens of microtesla, which is why a scanner room must exclude loose ferromagnetic objects.

Option A, the sievert, measures the biologically weighted equivalent dose of ionising radiation, which is irrelevant to MRI because it uses none. Option C, the becquerel, measures the activity of a radioactive source as one disintegration per second. Option D, the gray, measures absorbed dose of ionising radiation as one joule per kilogram. The three radiation units belong to X-ray, CT and nuclear medicine; only the tesla belongs to MRI. The older unit of flux density, the gauss, equals one ten-thousandth of a tesla.

The correct answer is B, Wilhelm Conrad Roentgen. Working with a discharge tube at the University of Wurzburg in November 1895, Roentgen noticed that a screen coated with a fluorescent salt glowed even when the tube was covered, and he traced the effect to an unknown penetrating radiation that he called X-radiation. For this he received the first Nobel Prize in Physics, awarded in 1901.

Option A, Marie Curie, with Pierre Curie discovered polonium and radium and won Nobel Prizes in Physics in 1903 and in Chemistry in 1911, but her work was on radioactivity and not on X-rays. Option C, Henri Becquerel, discovered natural radioactivity in uranium salts in 1896, a year after Roentgen, and his discovery was in fact prompted by the news about X-rays. Option D, J. J. Thomson, discovered the electron in 1897. Keep the sequence in mind: X-rays in 1895, radioactivity in 1896, the electron in 1897.

The correct answer is B, it runs the motor as a generator and returns energy to the battery. When the driver lifts off or brakes, the electric motor is made to work backwards: the turning wheels drive it, it generates electricity, and that current is fed back into the pack. Part of the vehicle's kinetic energy is therefore recovered instead of being lost as heat in the brake pads, which also means the friction brakes wear more slowly.

Option A describes an ordinary friction braking system, which an electric vehicle still carries for hard stops. Option C is not a feature of any electric vehicle; compressed air braking belongs to heavy trucks and railway stock, and works on an entirely different principle. Option D is wrong because during acceleration the battery is supplying energy, not receiving it; energy can be recovered only while the vehicle slows down or runs downhill. The gain is largest in city driving, with its constant stopping and starting.

The correct answer is B, sun-synchronous polar orbit. Such an orbit is near-polar, typically 600 to 900 kilometres high with an inclination of about 98 degrees, which makes it retrograde. Its plane precesses at the same rate at which the Earth revolves round the Sun, so the satellite crosses a given latitude at the same local solar time on every pass. Shadows and illumination are therefore comparable, which is what makes change detection possible. India's Cartosat, Resourcesat and Oceansat satellites use it.

Option A, geostationary orbit, gives a constant view of one hemisphere and suits communication and weather satellites such as INSAT, but it is far too high for detailed mapping. Option C, Molniya orbit, is a highly elliptical orbit inclined at about 63.4 degrees used to give long dwell time over high latitudes. Option D, graveyard orbit, is not a working orbit at all; it is a disposal orbit above the geostationary belt where retired satellites are parked.

The correct answer is B, the piezoelectric effect. Certain crystals develop a voltage across their faces when they are mechanically squeezed, and conversely change shape when a voltage is applied. An ultrasound probe uses this in both directions: an electrical pulse makes the crystal vibrate and send out a burst of ultrasound, and the returning echoes squeeze the crystal and generate the electrical signal from which the image is built.

Option A, the photoelectric effect, is the emission of electrons from a surface struck by light, explained by Einstein, and it matters in photocells and in how X-rays are absorbed, not in sound. Option C, the Zeeman effect, is the splitting of spectral lines in a magnetic field. Option D, the Raman effect, is the inelastic scattering of light that shifts its frequency, discovered by C. V. Raman. Note the related fact often asked alongside: ultrasound means sound above twenty kilohertz, the upper limit of human hearing.

The correct answer is C, 2012. Bharati was commissioned in 2012 at the Larsemann Hills on the coast of east Antarctica, roughly three thousand kilometres from Maitri. Having two stations so far apart lets Indian scientists study two very different sectors of the continent in the same summer season, which was the main reason for building it.

Option A, 1989, is the year Maitri was commissioned. Option B, 2008, is the year Himadri, India's Arctic station in Svalbard, was opened, so it belongs to the other pole. Option D, 2016, is the year the Himansh high-altitude glaciology station was set up in the Spiti area of Himachal Pradesh. All four years belong to this topic, which is why the question works; the chain to memorise is 1983-84 Dakshin Gangotri, 1989 Maitri, 2008 Himadri, 2012 Bharati, 2014 IndARC and 2016 Himansh.

The correct answer is B, the Ministry of Heavy Industries. The scheme for Faster Adoption and Manufacturing of Hybrid and Electric Vehicles is a demand and manufacturing support scheme, offering incentives that reduce the purchase price of eligible vehicles and funding charging infrastructure, and it sits with the ministry responsible for the automobile and capital goods industries.

Option A, the Ministry of Road Transport and Highways, frames motor vehicle rules, registration and safety standards and has exempted battery vehicles from registration fees, but it does not run FAME. Option C, the Ministry of New and Renewable Energy, handles solar, wind and the green hydrogen mission. Option D, the Ministry of Power, deals with the grid and issued the guidelines for charging infrastructure as a service. A related fact worth holding is that the production linked incentive scheme for Advanced Chemistry Cell battery storage is also with the Ministry of Heavy Industries.

The correct answer is B. Agnibaan SOrTeD, flown by Agnikul Cosmos of Chennai in 2024, carried the Agnilet engine, a semi-cryogenic engine printed as a single piece, and it lifted off from a launch pad the company had built for itself at the Satish Dhawan Space Centre. Both the printed engine and the private launch pad were firsts for India. Option A is wrong because solid propellant has been used in Indian rockets since the Rohini sounding rockets and the SLV-3; Agnibaan in fact uses a liquid and gaseous combination. Option C is wrong because SOrTeD was a sub-orbital technology demonstration and did not attempt orbit; the first Indian rocket to reach orbit was the SLV-3 in 1980. Option D is wrong because no Indian booster has yet landed back for reuse, although ISRO has tested landing technologies separately.

The correct answer is A, the Doppler effect. When sound is reflected from a moving target, the frequency of the echo is shifted: higher when the blood is moving towards the probe and lower when it is moving away. The machine measures this shift and converts it into a velocity, which is how a Doppler study detects a narrowed artery, a clot or a leaking heart valve, and how foetal heart sounds are picked up.

Option B, the Compton effect, is the scattering of an X-ray or gamma photon by an electron with a loss of energy, important in radiation shielding. Option C, the Tyndall effect, is the scattering of light by colloidal particles, which makes a beam visible in a dusty room. Option D, the Faraday effect, is the rotation of the plane of polarisation of light in a magnetic field. Only the Doppler effect concerns a shift in frequency caused by relative motion, which is also why it is used in radar speed guns and in astronomy.

The correct answer is A, Vitalik Buterin. Ethereum was described by Vitalik Buterin in a white paper of 2013 and the network went live in 2015. Its contribution was to add a general purpose computing layer, the Ethereum Virtual Machine, on top of a blockchain, so that programs called smart contracts could be stored on the chain and run by themselves; contracts are written in languages such as Solidity and the computation is paid for in a fee called gas. Its token is ether. Option B is wrong because Satoshi Nakamoto is the name on the bitcoin paper of 2008, and bitcoin has no general contract layer. Option C is wrong because Charlie Lee created Litecoin, an early alternative coin based on the bitcoin code. Option D is wrong because Hal Finney was an early bitcoin developer who received one of the first bitcoin transactions, not the founder of Ethereum.

The correct answer is C, 1 April 2019. The second phase shifted the emphasis from private cars to public and shared transport, concentrating its incentives on electric buses, two wheelers, three wheelers and commercial four wheelers, and tying them to conditions on battery type and on the share of parts made in India, while also funding charging stations.

Option A, 1 April 2015, is the start of the first phase, so it is the closest wrong answer and must be kept distinct. Option B, 1 April 2017, is a stray date. Option D, 1 April 2021, is associated with the production linked incentive schemes rather than with FAME. Fix the sequence: the National Electric Mobility Mission Plan 2020 announced in 2013, the first phase of FAME from 2015, the second from 2019, and a successor scheme continuing the work thereafter.

The correct answer is A, the Central Silk Board. The Silk Mark is issued by the Silk Mark Organisation of India, launched in 2004, which is a society set up by the Central Silk Board under the Ministry of Textiles; the Board itself was constituted in 1949 and has its headquarters at Bengaluru. The mark is a swing tag or label assuring the buyer that the fabric is pure natural silk and not a blend or an artificial imitation. Option B is wrong because the Bureau of Indian Standards issues the ISI mark, the hallmark and the Eco Mark but not the Silk Mark. Option C is wrong because the Textiles Committee tests and inspects textiles for export quality, a separate function. Option D is wrong because the Khadi and Village Industries Commission certifies khadi and village industry products, which is a different mark altogether.

The correct answer is B, Godfrey Hounsfield and Allan Cormack. Hounsfield, an engineer at EMI in Britain, built the first clinical CT scanner, and Cormack, a physicist, had independently worked out the mathematics of reconstructing a cross-section from measurements taken along many directions. The prize came in 1979, and the attenuation unit of CT is named after Hounsfield.

Option A, Lauterbur and Mansfield, won the same prize in 2003, but for magnetic resonance imaging, which is the pairing candidates most often swap. Option C, Bloch and Purcell, shared the 1952 Nobel Prize in Physics for discovering nuclear magnetic resonance in bulk matter, the physics that MRI later used. Option D is wrong on both counts: Roentgen won the first Physics prize in 1901 for X-rays and Becquerel shared the 1903 Physics prize for radioactivity. Learn the four as a table of prize, year and technique.

The correct answer is B, Reasi in Jammu and Kashmir. The Geological Survey of India reported an inferred lithium resource in the Salal and Haimana area of that district, the first lithium find of real consequence in the country and a significant one because India had been importing virtually all its lithium and its cells. Being an inferred resource, it still requires further exploration before mining can be planned.

Option A, Korba, is known for coal and for thermal power, not lithium. Option C, Nalgonda, is associated with uranium exploration in the Nalgonda and Nagarjuna Sagar region. Option D, Hassan, is linked with earlier reports of small lithium occurrences in Karnataka, which makes it a tempting distractor, but the February 2023 announcement concerned Jammu and Kashmir. Remember the companion fact: Khanij Bidesh India Limited, formed in 2019 by three public sector undertakings, acquires mineral assets abroad for the same purpose.

The correct answer is C, a gadolinium chelate. Gadolinium is a rare earth element whose ion is strongly paramagnetic, so it shortens the relaxation time of nearby hydrogen nuclei and brightens the tissue it reaches. Because the free ion is toxic, it is given bound in a chelate, and it is used to show tumours, inflammation and breaches in the blood-brain barrier.

Option A, barium sulphate, is the X-ray contrast swallowed or given as an enema to outline the gastrointestinal tract; it is insoluble and so is not absorbed. Option B, an iodine compound, is the X-ray and CT contrast injected for angiography and for contrast-enhanced CT, iodine being chosen for its high atomic number. Option D, technetium-99m, is a gamma-emitting radiopharmaceutical used in nuclear medicine scans with a gamma camera, not in MRI. Match each agent to its technique: barium and iodine with X-rays, gadolinium with MRI, technetium with nuclear scans.

The correct answer is B, Battery Management System. The BMS is the electronic brain of the pack. It measures the voltage, current and temperature of individual cells or groups of cells, balances their charge so that no cell is overworked, estimates the state of charge and state of health that the dashboard displays, and disconnects the pack when it detects an overcharge, a deep discharge, a short circuit or dangerous heating.

Option A is invented, although electric vehicles do carry brake sensors for regenerative braking. Option C is invented; India's charging specifications carry the Bharat name but there is no such standard abbreviation. Option D is invented. The reason the BMS matters in an exam answer is the concept attached to it: thermal runaway, a self-feeding rise in temperature inside a cell that can lead to fire, which the management system exists to prevent, and which is why battery safety standards were tightened after reports of scooter fires.