General Science Mixed Quiz: Set 95

Equal and opposite forces acting for the same time give equal and opposite changes in momentum, so the total stays the same.

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.

A work done that is fixed by the starting and ending speeds alone is exactly what the work-energy theorem states: W(net) = ½mv² − ½mu².

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.

A simple periscope has two plane mirrors, and light reaches the eye only by bouncing off them. In a simple periscope, two plane mirrors are fixed parallel to each other at the two bends of a long tube, each tilted at 45° to its length.

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.

The speed of the wave is frequency times wavelength, 700 m/s, and 2,100 m at 700 m/s takes 3 seconds.

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.

Inside a long current-carrying solenoid the magnetic field has the same strength and direction at every point, shown by parallel, evenly spaced field lines.

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

Their valencies are neon 0, magnesium 2, nitrogen 3 and silicon 4. Valency is the combining capacity of an atom, the number of electrons it loses, gains or shares to reach a stable octet.

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.

This statement is false: water is a strongly polar molecule. In a water molecule the oxygen atom is much more electronegative than hydrogen, so it pulls the shared electrons towards itself and carries a partial negative charge, while the two hydrogens carry partial positive charges.

Friction acts only where two surfaces touch, while a magnet can push or pull an object across a gap. Forces are grouped by whether the bodies must touch.

Metals produce a ringing sound when struck, a property called sonority, which is why bells are made of metal. Sonorous means 'producing a deep, ringing sound'.

Crown gall is caused by the bacterium Agrobacterium tumefaciens, which enters through a wound near the base, or crown, of the stem and makes the plant grow rough tumour-like swellings there.

Of the three forms of carbon, only fullerenes are made of closed, hollow, cage-like molecules. The best-known fullerene is buckminsterfullerene, C60, a hollow sphere of 60 carbon atoms arranged in 20 hexagons and 12 pentagons, shaped like a football.

Prokaryotes have no true nucleus, so there is no membrane around their genetic material. Prokaryotes are the simplest cells: bacteria and cyanobacteria (blue-green algae).

The pulmonary veins carry oxygen-rich blood from the lungs into the left atrium. In double circulation, blood passes through the heart twice in each full round.

Insulin is a protein (peptide) hormone made in the human body by the beta cells of the islets of Langerhans in the pancreas.