General Science Mixed Quiz: Set 19

By the sign convention the focal length of a concave lens is negative, so f is minus 15 centimetres, and the object distance measured against the direction of the incident light is minus 30 centimetres.

Distillation separates a liquid from a solution or from another liquid by boiling it and condensing the vapour, so it is used when the components differ in boiling point, as in getting pure water from salt water or separating acetone from water.

Pitch is the characteristic of a sound by which the brain judges it as shrill or flat, and it is decided by the frequency of the wave.

The name itself says so: in Greek arthros means jointed and podos means foot, so arthropods are the animals with jointed legs.

Among the allotropes of carbon, graphite has the lowest standard enthalpy of formation, which is taken as zero, so it is the reference state and the most stable form under ordinary conditions of temperature and pressure.

The zygote divides as it travels down the fallopian tube and the resulting ball of cells gets implanted in the thick lining of the uterus.

Barium compounds such as barium nitrate give fireworks and signal flares a bright green flame. The colour comes from a flame test.

Solder is an alloy of lead and tin, usually in nearly equal parts. An alloy is a mixture of a metal with one or more other elements, made to gain a property the pure metal lacks.

When a floating body tilts a little, the centre of buoyancy shifts to the centre of the newly displaced water, and the vertical drawn through it cuts the original axis of the body at a point called the metacentre.

Algae belong to Thallophyta, the simplest division of the plant kingdom. Their body is a thallus, which means it is not divided into root, stem and leaf, and they have no vascular tissue.

Calaverite is gold telluride, with the formula AuTe2. It is one of the very few minerals in which gold occurs chemically combined rather than as the free metal, because gold is a noble metal that usually resists reaction.

Force has to be applied to break the chalk because its particles hold one another together, and that pull is the force of attraction between particles.

Among the four, the ant has the largest brain in proportion to its body. An ant’s brain is tiny in absolute terms, with about two hundred and fifty thousand neurons, yet it makes up roughly a sixth of the insect’s body weight, a share no vertebrate comes close to.

A centre-tap full wave rectifier needs two p-n junction diodes, one for each half of the input cycle. The secondary winding of the transformer is tapped at its middle, so its two halves give equal voltages of opposite sign.

Both are tiny algae grown in tanks and sold as protein rich food supplements, and both have been studied as food for astronauts.

It states that the upthrust on a body dipped fully or partly in a fluid equals the weight of the fluid the body pushes aside.

A normal umbilical cord contains two arteries and one vein, three blood vessels in all. The umbilical cord joins the developing foetus to the placenta.

The BCG vaccine takes its name from Albert Calmette and Camille Guerin, the two French scientists who developed it from a weakened strain of Mycobacterium bovis.

Opium is the dried latex of the opium poppy, whose botanical name is Papaver somniferum; the second word means sleep bringing.

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