General Science Mixed Quiz: Set 148

It is an inorganic salt made of the ammonium ion and the cyanate ion, with no carbon–hydrogen bonds. Ammonium cyanate is famous in chemistry because in 1828 Friedrich Wöhler heated it and obtained urea.

Phycology, also called algology, is the study of algae, the simple photosynthetic organisms that range from the single-celled Chlamydomonas to the large brown seaweeds, and it covers their classification and their uses as food, fertiliser and a source of agar.

Both statements are true, and the second explains the first: infrared waves are called heat waves because water molecules, present in most materials, absorb them readily and heat up.

The hyoid is a U-shaped or horseshoe-shaped bone lying in the front of the neck below the lower jaw; it is held in place only by muscles and ligaments and forms no joint with any other bone, which is why it supports the tongue and helps in speech and swallowing.

Velocity ratio is defined as the distance moved by the effort divided by the distance moved by the load in the same interval of time, and because it depends only on the design of the machine it does not change with friction, unlike the mechanical advantage.

The spring constant is force divided by extension, so its SI unit is newton per metre. Hooke's law says that, within the elastic limit, the restoring force of a spring is proportional to how far it is stretched or compressed: F = −kx.

These bicarbonates are formed when water containing dissolved carbon dioxide passes over limestone, and they are unstable; on boiling they lose carbon dioxide and settle as insoluble carbonates, which is why this kind of hardness is called temporary and can be removed by boiling alone, or by the Clark method…

The correct answer is D, castor, which is the host of the eri silkworm and has nothing to do with lac culture.

Phloem sieve tubes are not like xylem vessels: sieve tubes are living cells with thin walls and sieve plates, while mature xylem vessels are dead, hollow tubes with thick lignified walls.

For small swings the time period is T = 2π√(L/g), which contains the length and gravity but neither the mass nor the amplitude.

Cobalt-60 is an artificial radioisotope that emits penetrating gamma rays and has a half-life of about 5.27 years, which makes it a convenient and long-lasting source for irradiation plants.

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 Haber process is exothermic, not endothermic: nitrogen and hydrogen combine to form ammonia and release heat. In the Haber process, N2 + 3H2 ⇌ 2NH3 gives out about 92 kJ for every two moles of ammonia formed.

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

The restoring force on the bob is mg sin θ. For small angles sin θ is almost equal to θ, so the force becomes proportional to the displacement and points back towards the mean position.

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.

Fly ash is the fine powdery residue left after coal is burnt in thermal power stations; it is a mixture of oxides, not a pure form of carbon.

A lever is a rigid bar turning about a fulcrum, and by the principle of moments the load multiplied by the load arm equals the effort multiplied by the effort arm, so a long effort arm lets a small effort balance a large load; this is the simplest way of…

Water contracts as it is cooled to four degrees, is densest at that temperature, and then expands again as it cools further to zero, which is called the anomalous expansion of water.

Urea, CO(NH₂)₂, contains carbon, oxygen, nitrogen and hydrogen; it has no phosphorus at all and is a nitrogenous fertilizer. Urea carries about 46% nitrogen, the highest of the common solid fertilizers, which is why it is the most widely used fertilizer in India.