Penicillin, the first widely used antibiotic, was discovered by whom?

The correct answer is D, J. J. Thomson. In 1897 Thomson passed an electric discharge through a gas at very low pressure and showed that the cathode rays produced were a stream of identical negatively charged particles, far lighter than any atom and the same whatever gas or electrode was used. He called them corpuscles; they were later named electrons, and he measured their charge to mass ratio. Option A, Chadwick, discovered the neutron in 1932 and not the electron. Option B, Niels Bohr, did not discover any particle; he proposed the model in which electrons revolve in fixed energy shells and explained the hydrogen spectrum. Option C, Rutherford, used the scattering of alpha particles by gold foil to establish the small, dense, positively charged nucleus and gave the proton its name. The order to memorise is electron by Thomson in 1897, nucleus and proton by Rutherford, and neutron by Chadwick in 1932.

The correct answer is C, James Chadwick. In 1932 Chadwick bombarded beryllium with alpha particles and showed that the highly penetrating radiation given off consisted of neutral particles with almost the same mass as a proton. The neutron explained why the mass of an atom is greater than the mass of its protons, and it explained isotopes, so Chadwick received the Nobel Prize in Physics for it. Option A, Marie Curie, worked on radioactivity with her husband Pierre and isolated polonium and radium; she did not discover a nuclear particle. Option B, Rutherford, discovered the nucleus through the gold foil experiment and predicted that a neutral particle must exist, but it was his student Chadwick who found it. Option D, Max Planck, founded the quantum theory by proposing that energy is radiated in packets called quanta. The three-line summary is Thomson for the electron, Rutherford for the nucleus and Chadwick for the neutron.

The correct answer is C, Faraday and Henry. Working independently in the 1830s, Michael Faraday in England and Joseph Henry in the United States showed that a changing magnetic flux through a circuit sets up an electromotive force in it, and that the effect depends on the rate of change of flux rather than on the flux itself. This single result is the basis of the dynamo, the alternating current generator, the transformer and the induction motor, and the unit of inductance, the henry, is named after Henry. Option A, Rutherford, belongs to nuclear physics and not to electromagnetism. Option B, Einstein, is remembered for the photoelectric effect, for relativity and for the mass energy relation. Option D pairs Planck, the founder of quantum theory, with Fermi, who built the first nuclear reactor, neither of whom worked on induction. Remember that Faraday also gave the laws of electrolysis, so his name appears in chemistry questions too.

The correct answer is B, amber. Elektron is the Greek name for amber, the fossilised tree resin which the ancient Greeks found would attract straw, feathers and bits of dust after being rubbed with fur. Because amber was the first material in which this attraction was noticed, the whole science that grew out of it was named electricity, and the particle Thomson discovered in 1897 was named the electron. Option A, ebonite, is a hard vulcanised rubber used in school experiments on static electricity; it is a modern material and not the source of the word. Option C, charge, is the physical quantity that the phenomenon involves, but it is not what the Greek word means. Option D, negative, describes the sign of the charge an electron carries, which was fixed by convention long after the Greek word was coined. Questions on the origin of scientific words are set often, so remember amber for elektron and atomos, meaning indivisible, for atom.

The correct answer is B, barometer. A barometer measures the pressure of the atmosphere, and the mercury barometer invented by Evangelista Torricelli in 1643 does so by balancing the weight of the air against a column of mercury about 76 centimetres high at sea level. A sudden fall in the reading means that a storm is approaching, while a steady high reading means fine weather, so the instrument is the foundation of weather forecasting. Option A, hygrometer, measures the humidity or the amount of water vapour in the air. Option C, anemometer, measures the speed of the wind, usually with three or four cups that spin on a vertical axis. Option D, lactometer, measures the relative density of milk and so indicates whether it has been diluted. The trap to watch for is manometer, which also measures pressure but the pressure of an enclosed gas rather than that of the open atmosphere.