General Science Mixed Quiz: Set 93

One nanometre is 10⁻⁹ metre, and since one metre is 100 (10²) centimetres, it equals 10⁻⁷ centimetre. The prefix nano means one billionth.

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.

Velocity multiplied by time is displacement, so the area between a velocity-time graph and the time axis gives the displacement.

Red biotechnology is the branch applied to medicine and health care, including the making of insulin, antibiotics and vaccines. Biotechnology is often divided by colour according to its field of use.

Power equals force times velocity, so the force is 3,000 W divided by 5 m/s, which is 600 N. Power is the rate of doing work: P = W/t. Work is force times distance, W = F × d, so P = F × d/t, and since d/t is the…

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.

Starlight is bent again and again by layers of air of changing density, so its path and brightness keep shifting and the star seems to twinkle.

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.

At a fixed temperature, changing the pressure of an ideal gas does not change the speed of sound in it, so x and y are equal.

An ion-exchange resin or zeolite swaps the calcium and magnesium ions that cause permanent hardness for sodium or hydrogen ions.

A Van de Graaff generator is an electrostatic machine that builds up a very large static charge on a hollow metal sphere, raising it to millions of volts.

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.

The chloride ion has 18 electrons, while the magnesium ion has only 10, so the two are not isoelectronic. Isoelectronic species have the same number of electrons.

Pinctada margaritifera is the black lip pearl oyster, a bivalve mollusc of the warm shallow water of the Indo-Pacific, where it fastens itself to coral reefs by strong threads.

Magnesium combines with oxygen to form a new substance, magnesium oxide, so a chemical reaction takes place. When a magnesium ribbon is heated, it burns with a dazzling white flame and leaves a white powder: 2Mg + O₂ → 2MgO.

In a class 3 lever the effort is applied between the fulcrum and the load, so the effort always sits nearer the fulcrum and its arm is the shorter of the two.

Sodium reacts vigorously with cold water to form sodium hydroxide and hydrogen gas: 2Na + 2H₂O → 2NaOH + H₂.

Diamond and graphite are allotropes of the same element, carbon, so their chemical properties are the same; only their physical properties differ.

This is sodium stearate, the sodium salt of a long-chain fatty acid, which makes it a soap and not a synthetic detergent.

The breakdown of glucose into pyruvate, called glycolysis, takes place in the cytoplasm (cytosol) of the cell. Glycolysis is the first step of respiration in almost every living cell.