General Science Mixed Quiz: Set 169

In SI units the universal gas constant is 8.314 joule per mole per kelvin, obtained by multiplying the Boltzmann constant by the Avogadro number.

Pedology is the study of soils, including their formation from parent rock, their profile and horizons, their classification and their fertility, and it is the science behind soil surveys and land capability maps.

The rusts of wheat, named black, brown and yellow after the colour of the pustules they raise on the stem and leaves, are caused by species of Puccinia, and resistance to them was one of the traits selected in the dwarf wheats of the Green Revolution.

About an axis through the centre, a solid disc has I = ½MR² while a solid sphere has I = ⅖MR², and ½ is larger than ⅖.

Ammonium sulphide is an unstable, foul-smelling compound that breaks down to release ammonia and toxic hydrogen sulphide, so it is not used as a fertiliser.

The correct answer is B, Bombyx mori, the mulberry silkworm, the only fully domesticated insect of the silk group and the source of most of the world's raw silk.

Substituting one mole, 273.15 kelvin and one atmosphere in the ideal gas equation gives a volume of 22.4 litres, the molar volume at standard temperature and pressure, and this is the figure used in mole calculations; with the modern standard pressure of one bar the value works out to about…

This is the defining condition of simple harmonic motion, written F = −kx, where k is the force constant and the minus sign shows that the force always points back towards the mean position.

The correct answer is A, Colletotrichum falcatum, a fungus that rots the internal tissue of the cane, turning it red with white patches and giving it a sour smell, and which spreads mainly through infected setts used for planting.

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.

Graham's law of diffusion states that at the same temperature and pressure the rate at which a gas diffuses is inversely proportional to the square root of its density, and therefore of its molar mass.

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

Citrus canker is caused by a species of Xanthomonas, which enters through wounds, insect punctures and stomata and raises raised corky brown lesions, often with a yellow halo, on leaves, twigs and fruit; it spreads in splashing rain, on tools and on infected nursery plants.

Pressure is force acting per unit area, so its SI unit is the newton per square metre, which is given the special name pascal (Pa) after the French scientist Blaise Pascal, who stated the law of transmission of pressure in liquids used in hydraulic brakes and lifts.

The kinetic theory gives the average kinetic energy of a molecule as three halves of the product of the Boltzmann constant and the absolute temperature, and for one mole as three halves of RT.

Pellagra is caused by a lack of vitamin B3, also called niacin or nicotinic acid. The body can also make niacin from the amino acid tryptophan, so the disease is common where people live mainly on maize, which is poor in both.

In khaira disease the leaves of young rice plants develop rusty brown spots that spread until the crop looks scorched, tillering is poor and growth is stunted; an application of zinc sulphate to the soil or as a foliar spray corrects it, which confirms that the cause is a deficiency…

Temperature is a measure of the average kinetic energy of the particles of a substance, in a solid as in a gas: in a solid the particles are held in fixed positions but vibrate about them, and heating makes the vibrations faster and wider, so the average kinetic energy rises…

Where this micronutrient is short, the leaf blade of cauliflower fails to expand and the leaf is reduced to a narrow, whip-like strip along the midrib, which gives the disease its name; the curd is small or does not form at all.

The kinetic theory of an ideal gas assumes exactly the opposite: that there are no forces of attraction or repulsion between molecules except during the brief moment of a collision.