General Science Mixed Quiz: Set 143

Heat is energy in transit: it flows from a hotter body to a colder one only because their temperatures differ, and stops when they reach the same temperature.

Sericulture is the rearing of silkworms for the production of raw silk, and it includes the growing of mulberry, on whose leaves the mulberry silkworm feeds; India produces mulberry silk as well as the wild varieties tasar, eri and muga, the last being special to Assam.

In the Raman effect, a small part of the light scattered by molecules comes out with a changed frequency. C.V.

The Austrian scientist Karl Landsteiner discovered the A, B and O blood groups in 1901 and received the Nobel Prize for Physiology or Medicine in 1930 for the work; he was also associated with the discovery of the Rh factor, named after the rhesus monkey.

Sound in liquids and gases travels as a longitudinal wave, not a transverse one. In a longitudinal wave the particles of the medium vibrate back and forth along the direction in which the wave moves, forming compressions and rarefactions.

Pliers and scissors are each made of two arms joined at one rivet, and each arm is a complete class 1 lever, so the tool is called a double lever.

Both quantities change with temperature, and resistance is directly proportional to resistivity, while resistivity does not depend on the wire’s size.

Boiling removes only temporary hardness; permanent hardness comes from salts that do not break down on heating. Temporary hardness is caused by the bicarbonates of calcium and magnesium.

A substance that loses hydrogen is oxidised, not reduced, so statement A is the incorrect one. In the classical definitions, oxidation means the gain of oxygen or the loss of hydrogen, and reduction means the loss of oxygen or the gain of hydrogen.

The pinna is the outer, visible flap of the ear, and its funnel shape collects sound from the surroundings. Sound gathered by the pinna travels down the ear canal to the tympanic membrane, or eardrum, which starts to vibrate.

Goldsmiths dip gold and silver ornaments in dilute nitric acid to dissolve the dirt, oxide layers and traces of base metals stuck to them, which brings back their shine.

In the chlor-alkali process a concentrated solution of sodium chloride is electrolysed; chloride ions are oxidised at the anode and come off as chlorine gas, hydrogen is set free at the cathode, and sodium hydroxide remains in the solution, which is why the industry yields three useful products at once.

Here water only combines with calcium sulphate hemihydrate to form gypsum; no gas is given off and the paste simply sets hard.

Root hairs are thin outgrowths of the root's epidermal cells that greatly increase the area for absorbing water and minerals.

Methane and chlorine react in sunlight to give chloromethane and hydrogen chloride, not hydrogen gas. This is a substitution reaction: CH4 + Cl2 → CH3Cl + HCl in the presence of sunlight.

In uniform circular motion the speed stays the same, but the direction of the velocity keeps changing, so the car is always accelerating and the direction of that acceleration keeps changing too.

Gypsum heated at 373 K becomes calcium sulphate hemihydrate, CaSO4 · ½H2O, which is plaster of Paris, not CaSO4 · H2O as the statement says.

These four elements make up the complex tissue that carries water and minerals upward from the roots. Tracheids and vessels are long, dead, thick-walled tubes through which water moves; xylem parenchyma is the only living part and stores food; xylem fibres give support.

The Bohr effect is the fall in haemoglobin's affinity for oxygen when carbon dioxide and acidity rise, so oxygen is unloaded where tissues need it most.

Renin, released by the kidney, converts angiotensinogen made by the liver into angiotensin I, which is then changed into angiotensin II.