General Science Mixed Quiz: Set 105

Average force equals the change in momentum of the coin divided by the time of contact.

Meiosis makes gametes that differ from one another, and fertilization joins a gamete from each of two parents, so every offspring gets a new mix of genes.

The heat needed to turn unit mass of a liquid into vapour at constant temperature is its specific latent heat of vaporisation.

The de Broglie wavelength depends only on momentum, so equal wavelengths mean equal momenta. In 1924 Louis de Broglie proposed that every moving particle has a wave linked to it, with wavelength λ = h/p, where h is Planck's constant and p is the linear momentum.

Outside a long straight wire the field is B = μ₀I/(2πr), so at a fixed distance r it is directly proportional to the current I. Hans Christian Oersted found in 1820 that a current deflects a compass needle, showing that a current produces a magnetic field.

Rotational kinetic energy is ½Iω², and the ring has the larger moment of inertia. For a thin ring about the axis through its centre and perpendicular to its plane, all the mass sits at distance R, so I = MR².

Toothpaste is mildly basic so that it can neutralise the acid that causes tooth decay. Bacteria in the mouth break down sugar and food particles left on the teeth and produce acids.

For small swings the time period is T = 2π√(L/g), which contains the length and gravity but neither the mass nor the amplitude.

This is the order in which these metals stand in the reactivity series, and it matches how vigorously they release hydrogen from dilute hydrochloric acid.

A beam seen from the side is visible only because tiny particles send some of its light sideways. Light travelling in a straight line cannot enter our eyes unless something redirects it towards us.

Adenosine triphosphate stores energy in its phosphate bonds and releases it wherever the cell needs it, so it is called the energy currency of the cell.

Gamma rays sit at the far end of the electromagnetic spectrum, with the shortest wavelength and therefore the highest frequency and energy.

Without enough vitamin D the body cannot absorb calcium and phosphorus properly, so a child's growing bones stay soft and bend.

Lemongrass and its close relative citronella grass yield aromatic oils that keep mosquitoes away, so they are the base of many natural repellents.

Chlorophyll absorbs light energy, which is used to split water and then to reduce carbon dioxide to sugar. In the light reactions, energy trapped by chlorophyll splits water molecules (photolysis), releasing oxygen, hydrogen ions and electrons and producing ATP and NADPH.

Jupiter is a planet; it does not make its own light and shines only by reflecting sunlight. A luminous object produces light of its own, as stars do by nuclear fusion in their cores, where hydrogen is turned into helium.

Two liquids that mix completely but boil at clearly different temperatures can be separated by heating the mixture and condensing the vapour of the lower-boiling liquid first.

A convex lens forms an image at the same distance as the object only when the object sits at 2f, and here 2f works out to 4R/3.

RTGs power spacecraft using heat from the natural decay of plutonium-238; they are not reactors and involve no fission. In an RTG, a radioactive isotope gives off heat as it decays on its own.

Aluminium has three valence electrons, one fewer than silicon, so each aluminium atom leaves a hole that acts as a positive charge carrier.