Set 177 of the General Science mixed quiz has 20 multiple-choice questions from 11 different topics of the subject: Modern Physics: Photoelectric Effect, Lasers and Superconductivity, Fluids: Buoyancy, Viscosity and Surface Tension, Atoms and Molecules: Laws of Chemical Combination and the Mole Concept and more. 2 of them were asked in real previous-year papers. A topic quiz checks one chapter; this set revises the whole subject at once, the way an exam paper does, where the next question can come from any chapter. Every question carries an explanation of why the correct option is right and why the others are wrong. Keep to the timer, read the explanations at the end, and go back to the notes of any topic where you slipped.
20 questions with answers and explanations
The first working laser, a ruby laser, was built in 1960 by
Maiman built the first operating laser in 1960, using a rod of synthetic ruby, that is chromium ions in aluminium oxide, pumped by a flash lamp, and it emitted pulses of deep red light.
Read the full explanation →Centre of buoyancy is
The upthrust on a body is the resultant of the pressure forces of the fluid around it, and that resultant acts through the centre of gravity of the fluid the body has pushed aside, which is why the point is called the centre of buoyancy.
Read the full explanation →At standard temperature and pressure, the volume occupied by one mole of any gas is
It follows from Avogadro's law: since equal volumes of all gases at the same temperature and pressure contain an equal number of molecules, one mole of hydrogen, of oxygen or of carbon dioxide all take up the same space at standard temperature and pressure, even though their masses are two…
Read the full explanation →Which was the first nuclear power station to be set up in India?
The Tarapur Atomic Power Station was the first nuclear power station in India and also the first in Asia, built with American collaboration and using boiling water reactors, unlike the pressurised heavy water reactors of the later Indian stations.
Read the full explanation →The property of laser light by which all its waves are in the same phase is called
Coherence means that the waves in the beam keep a constant phase relationship, so crest marches with crest; this is a direct result of stimulated emission, since each new photon is emitted in phase with the photon that caused it, and it is what makes holography and interference work with…
Read the full explanation →The transistor was invented in 1947 at Bell Laboratories by:
John Bardeen, Walter Brattain and William Shockley built the first working transistor at Bell Laboratories in 1947 and shared the Nobel Prize in Physics in 1956 for the discovery of the transistor effect.
Read the full explanation →One unified atomic mass unit, written as u, is defined as
This standard was adopted so that the atomic masses of all elements could be compared on one relative scale, and on it hydrogen comes out as about 1 u, oxygen as 16 u and chlorine as 35.5 u. Option A is wrong because the hydrogen atom was the standard in…
Read the full explanation →Zone refining is used to obtain metals of very high purity and depends on which principle?
Zone refining rests on the fact that impurities are more soluble in a molten metal than in the same metal when solid.
Read the full explanation →Superconductivity was discovered in 1911 in mercury cooled to about 4.2 kelvin by
The Dutch physicist Kamerlingh Onnes, who had already succeeded in liquefying helium, cooled mercury with it in 1911 and found that its electrical resistance disappeared completely below about 4.2 kelvin, the first observation of superconductivity.
Read the full explanation →Liquefied petroleum gas (LPG) used as domestic cooking fuel consists mainly of which gases?
Liquefied petroleum gas is obtained during the refining of petroleum and from natural gas processing, and it is chiefly a mixture of butane and propane, which liquefy under moderate pressure at ordinary temperature and so can be stored in a cylinder.
Read the full explanation →How many moles are present in 36 grams of water?
The molecular mass of water is eighteen unified atomic mass units, two hydrogen atoms of 1 u each and one oxygen atom of 16 u, so one mole of water weighs eighteen grams.
Read the full explanation →Which of the following natural fibres is a protein?
Wool is the fleece of sheep and other animals and is made of the protein keratin, so it is a protein fibre; silk, which is the protein fibroin, is the other natural fibre of this kind, and both come from animals.
Read the full explanation →The expulsion of magnetic flux from the interior of a superconductor is known as
When a material becomes superconducting it pushes the magnetic field out of its interior and behaves as a perfect diamagnet, an effect reported by Meissner and Ochsenfeld in 1933; it is the reason a small magnet can be made to hover above a cooled superconductor, as in magnetic levitation demonstrations.
Read the full explanation →Which scientist crystallised the tobacco mosaic virus and showed it to be largely protein?
Wendell Meredith Stanley crystallised the tobacco mosaic virus and showed that the crystals were made chiefly of protein, work that proved a virus could be handled like a chemical substance and won him a share of a Nobel Prize.
Read the full explanation →Carbon forms two oxides, carbon monoxide and carbon dioxide, in which twelve grams of carbon combines with sixteen grams and thirty two grams of oxygen respectively. This illustrates
When two elements form more than one compound, the masses of one element that combine with a fixed mass of the other bear a simple whole number ratio, and here the oxygen masses of sixteen and thirty two grams for the same twelve grams of carbon are in the ratio…
Read the full explanation →Which pair of proteins slides over each other during the contraction of a skeletal muscle?
In the sliding filament theory of contraction, a nerve impulse causes calcium to be released from the sarcoplasmic reticulum; the calcium exposes binding sites on the thin actin filaments, the heads of the thick myosin filaments attach to them and swivel, using energy from ATP, and the actin is pulled…
Read the full explanation →The essential condition for the action of a laser is
In ordinary matter most atoms sit in the lower energy level, so light passing through is absorbed more than it is amplified.
Read the full explanation →The Medical Termination of Pregnancy Act was amended in which year to raise the upper limit to twenty-four weeks for certain categories of women?
The amendment of 2021 kept termination up to twenty weeks on the opinion of one registered medical practitioner, allowed it between twenty and twenty-four weeks for certain categories of women such as survivors of rape or incest on the opinion of two practitioners, and removed the upper limit where a…
Read the full explanation →Equal volumes of all gases, under the same conditions of temperature and pressure, contain an equal number of molecules. This statement is known as
It is the reason one mole of every gas occupies the same 22.4 litres at standard temperature and pressure, and it allowed chemists to settle the formulae of gases such as hydrogen and oxygen as having two atoms each.
Read the full explanation →Which one of the following statements about the law of conservation of mass is correct?
The law of conservation of mass, stated by Antoine Lavoisier in 1789, says that in a chemical reaction mass is neither created nor destroyed.
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