General Science Mixed Quiz: Set 175

Anthracene sublimes on heating, while common salt does not, so heating the mixture separates them. Sublimation is the change of a solid directly into vapour without passing through the liquid state.

The Swedish naturalist Carolus Linnaeus introduced the two part naming of organisms in Systema Naturae and applied it to the plant kingdom in Species Plantarum, and because he also built the ranked system of classification he is called the father of taxonomy.

The name comes from the Greek words for naked and seed: gymnosperms bear seeds that are not enclosed in a fruit, and most of them are woody, evergreen trees.

Cryogenics deals with the production of very low temperatures and with the behaviour of materials at those temperatures, where liquefied gases such as liquid nitrogen, oxygen and hydrogen are used; it is applied in rocket engines with cryogenic upper stages, in superconducting magnets and in the preservation of biological material…

X-rays have wavelengths of roughly 0.01 to 10 nanometres, and a typical value is about one ångström (1 Å = 10⁻¹⁰ m = 0.1 nm).

The emf of a battery equals the power it supplies divided by the current it drives, because power P = EI.

Rain water is the purest natural form of water because it is formed by evaporation and condensation, a natural distillation.

Xylem carries water together with the minerals dissolved in it from the roots to the stem and leaves, so blocking it stops both.

The law states that for a mixture of gases that do not react, the total pressure is the sum of the partial pressures each gas would exert if it alone occupied the whole volume at the same temperature.

When a wire is stretched its volume stays the same, so the length must grow in the same ratio as the cross-sectional area shrinks.

Bordeaux mixture is a suspension made by adding a solution of copper sulphate to one of lime, and it is the oldest fungicide still in regular use; it was devised in the Bordeaux region of France against downy mildew of the grapevine and is sprayed today on fruit trees, potatoes…

With no external force on the system, its centre of mass cannot start moving. The throw is an internal force: X pushes the tool forward and the tool pushes X backward with an equal and opposite force (Newton's third law).

The citation for the prize refers to his services to theoretical physics and especially to his discovery of the law of the photoelectric effect, the equation in which the energy of a photon equals the work function plus the maximum kinetic energy of the emitted electron.

The eri silkworm, Samia ricini, feeds on castor leaves, and its silk is called ahimsa silk because the moth is allowed to emerge before the cocoon is used, leaving a broken fibre that is spun like cotton instead of being reeled.

Water drawn from a river, from rain or made in a laboratory always has hydrogen and oxygen in the mass ratio of one to eight, and ammonia always has nitrogen and hydrogen in the ratio of fourteen to three.

This is the defining condition of simple harmonic motion, written F = −kx, where k is the force constant and the minus sign shows that the force always points back towards the mean position.

In the light reaction of photosynthesis, water is broken up; its hydrogen is used to make food and its oxygen is given out.

Almost all the world's ammonia is made by combining nitrogen and hydrogen directly in this process. In the Haber-Bosch process, nitrogen from the air and hydrogen, usually obtained from natural gas, are made to react in the ratio 1 to 3.

A rod standing upright on one end falls over at the slightest push, because its centre of gravity is high and its base is tiny.

For a swinging pendulum, the component of the bob's weight along its path always pulls it back towards the lowest point, so gravity acts as a restoring force.