General Science Mixed Quiz: Set 8

The mole is the chemist's counting unit: one mole of any substance contains the Avogadro number of particles, about six followed by twenty-three zeros, whether those particles are atoms, molecules or ions.

Levers are grouped by where the fulcrum, the load and the effort sit. In a second class lever the load lies between the fulcrum and the effort.

A concave lens spreads the light rays slightly before they enter the eye, so the image moves back onto the retina.

LIGO, the Laser Interferometer Gravitational-Wave Observatory in the USA, detected gravitational waves for the first time in September 2015 (announced in February 2016), and such waves were predicted by Einstein's general theory of relativity in 1916.

The inner transition elements are the lanthanides and actinides, in which electrons fill the f-orbitals, so they form the f-block of the periodic table.

A healthy human ear can hear sound waves with frequencies from about 20 hertz to 20,000 hertz (20 kHz); this band is called the audible range.

Aluminium naturally forms a thin layer of aluminium oxide when it is exposed to air, and this layer protects it from further corrosion.

In 1831 the British scientist Michael Faraday showed that a changing magnetic field produces an electric current in a nearby coil.

Kwashiorkor is caused by a severe lack of protein in the diet, even when the child gets some calories from starchy food.

Milk of magnesia is a milky white suspension of magnesium hydroxide, Mg(OH)2, in water. It is a mild base, so it neutralises the extra hydrochloric acid in the stomach that causes acidity and heartburn; the reaction gives magnesium chloride and water.

Geitonogamy is the transfer of pollen grains from the anther of one flower to the stigma of another flower on the same plant.

In diamond every carbon atom is joined to four other carbon atoms by strong covalent bonds. These bonds point towards the corners of a tetrahedron and build a rigid three-dimensional network that runs through the whole crystal.

Isaac Newton built the first practical reflecting telescope in 1668. In it, light from the star falls on a large concave mirror at the bottom of the tube, and a small flat mirror set at 45 degrees near the top turns the light sideways to the eyepiece.

Laughing gas is nitrous oxide, N2O, a colourless gas with a faintly sweet smell that makes people giggle and feel light-headed when they breathe it in.

A qubit, short for quantum bit, is the basic unit of information in a quantum computer.

The nucleus is called the master or control centre of the cell because it directs all the activities of the cell.

The horsepower is an older practical unit of power that survives in the rating of engines, pumps and motors, and it equals about 746 watts.

Atomicity is the number of atoms in one molecule of an element, and it is why we write nitrogen gas as N2 and not just N. Nitrogen gas exists as N2, two atoms joined by a strong triple bond, so it is diatomic, like oxygen, hydrogen and chlorine.

Thiamin (thiamine) is vitamin B1, a water-soluble vitamin that helps the body turn carbohydrates into energy and keeps the nerves and heart working well.

Anabaena is a cyanobacterium, a prokaryote with no true nucleus, and all prokaryotes are placed in Monera. In R.H.