General Science GK Questions with Answers – Page 60

Both gain the same kinetic energy, but the electron is far lighter, so it moves much faster. A charge q accelerated through a potential difference V gains kinetic energy qV.

A perfectly horizontal rope has no upward component of tension, so no finite tension can hold up the 200 N weight with the rope fully straight.

Digestion begins in the mouth, where saliva adds salivary amylase to the food as it is chewed. Salivary amylase, also called ptyalin, starts breaking starch into maltose while food is still in the mouth.

The stinging hairs on nettle leaves inject methanoic acid, also called formic acid, into the skin, which causes the burning pain.

Starlight bends as it passes through air layers of changing density, and because these layers keep moving, the star seems to flicker.

Momentum is mass times velocity, 10 × 10 = 100 N.s, and kinetic energy is half the mass times the square of the speed, ½ × 10 × 10 × 10 = 500 J. Linear momentum, p = mv, measures the quantity of motion and is a vector; its unit…

X-rays can pass through solid materials and their wavelength is close to the spacing of atoms, so they serve both purposes.

This is the statement that is not correct; the other three describe the benzene molecule correctly, and UPSC's official key also gives D. Benzene, C6H6, is a flat ring of six carbon atoms.

Statement 2 is the only incorrect one, because a compound always has a fixed composition, not a variable one. An element is the simplest form of matter and cannot be broken down into simpler substances by chemical reactions, so statement 1 is correct.

A cosmic ray physicist who founded the Physical Research Laboratory at Ahmedabad, he persuaded the government that a poor country needed space technology for communication, weather and education, set up the rocket launching station at Thumba and built the organisation that became the Indian Space Research Organisation.

Raman announced in 1928 that light scattered by a transparent medium contains components of changed wavelength, a shift that reveals the energy levels of the scattering molecules, and the Nobel Prize in Physics followed in 1930, making him the first Asian to receive a Nobel in a science.

His study of the characteristic X-rays of the elements showed that the nuclear charge, the atomic number, is the quantity that rises regularly from element to element, and the modern periodic law therefore states that properties are a periodic function of atomic number.

Ohm found that for a metallic conductor at a steady temperature the ratio of potential difference to current is a constant, the resistance, which is written as V equals I into R, so doubling the voltage doubles the current.

His experiments on garden pea, in which he followed single characters such as seed shape and flower colour through generations, gave the laws of dominance, segregation and independent assortment, and showed that inheritance works through discrete factors rather than a blending of parental traits.

Pressure applied to an enclosed liquid is transmitted equally and undiminished in every direction, so a small force on the narrow master cylinder of a brake creates a much larger force on the wide piston at each wheel, which is also how a hydraulic press and a hydraulic lift work.

Working on the observations of Tycho Brahe he found that a planet moves in an ellipse with the sun at one focus, that the line from the sun to the planet sweeps equal areas in equal times, and that the square of the orbital period is proportional to the cube…

By bombarding beryllium with alpha particles he obtained a penetrating radiation that could not be bent by electric or magnetic fields, and he showed it to consist of neutral particles of about the mass of a proton, for which he received the Nobel Prize in Physics.

Thomson. Working with cathode rays in a discharge tube in 1897, he showed that the rays were a stream of negatively charged particles far lighter than any atom, and he measured their charge to mass ratio, which established the electron as the first known subatomic particle.

In Einstein's special theory of 1905 the energy required to accelerate a body with mass rises without limit as its speed approaches that of light, so such a body can come close to but never reach the speed of light in vacuum, which is the same for every observer.

Phreatophytes are deep-rooted plants that survive in dry regions by drawing water from the water table. The name comes from the Greek for 'well plant'.