General Science Mixed Quiz: Set 159

The body falls freely from rest through 50 m, so v² = 2gh = 2 × 9.8 × 50 = 980, giving v = √980, about 31.3 m s⁻¹; its total energy at release is all potential energy, mgh = 2 × 9.8 × 50 = 980 J. Because the…

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…

Since both wires have the same material and thickness, resistance is proportional to length, so R2 = 2R1, and the parallel combination works out to R = 2R1/3.

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.

Arranged from most acidic to most basic, the four substances fall in exactly this order. Lemon juice, rich in citric acid, has a pH of about 2 to 2.5.

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

All four are parts of the two complex permanent tissues of plants: tracheids and vessels belong to xylem, while sieve tubes and companion cells belong to phloem.

The principle says a body immersed wholly or partly in a fluid is pushed up by a force equal to the weight of the fluid it pushes aside, and that upward force is called buoyancy or upthrust.

Tidal volume, the air breathed in or out in one normal quiet breath, is only about 500 millilitres in a healthy adult, the smallest of the four volumes listed.

A Zener diode is heavily doped so that breakdown occurs at a low and sharply defined reverse voltage. Beyond that point the voltage across it stays almost constant even when the current through it changes a great deal, which is precisely the property a voltage regulator needs.

Nerve impulses are carried by the movement of sodium and potassium ions across the membrane of the nerve cell, so sodium is essential.

Malleability is the property of being beaten into thin sheets and ductility the property of being drawn into wires, and gold possesses both to the highest degree of any metal: a single gram can be beaten into a sheet of about one square metre and drawn into a wire of…

Kwashiorkor is a disease of protein deficiency in a child who still gets enough calories. It usually appears when a child is weaned from breast milk onto a starchy diet with little protein.

Rayon is made by dissolving the cellulose of wood pulp, forcing the solution through fine holes and regenerating the cellulose as a thread.

Buoyancy, also called upthrust, is the upward force that a liquid or gas exerts on any object placed in it.

In a lichen the algal partner, called the phycobiont, photosynthesises and supplies food, while the fungal partner, the mycobiont, gives shelter and absorbs water and minerals; lichens grow on bare rock as pioneers and die in polluted air, so they serve as indicators of air pollution.

Starlight bends as it passes through layers of air of changing temperature and density, and because these layers keep moving, the star's apparent position and brightness flicker.

Biogas is mainly methane and carbon dioxide. Biogas is produced when bacteria break down animal dung, crop waste and kitchen waste in the absence of oxygen, a process called anaerobic digestion.

Bisphenol A is the main building block from which polycarbonate plastic is made. Polycarbonate is a hard, clear and shatter-resistant plastic once widely used for reusable water bottles, baby feeding bottles, food containers, CDs and spectacle lenses.

Frogs and most fishes release their eggs and sperm into water, where fertilisation takes place outside the female's body. In external fertilisation, a large number of eggs and sperm are shed together, because many are lost to currents and predators.