General Science Mixed Quiz: Set 165

Speed tells only how fast a body moves, while velocity also tells the direction of motion, and a quantity with both magnitude and direction is a vector.

Seismology is the study of earthquakes and of the passage of seismic waves through the earth, and it is from seismic wave records that the layered structure of the interior of the earth has been worked out; the instrument used is the seismograph.

Electric charge equals current multiplied by time, Q = I × t, with time in seconds: 0.6 A × 600 s = 360 coulombs.

Hydrated oxalic acid has a molar mass of 126 and is a dibasic acid, so its equivalent weight is 126 ÷ 2 = 63.

Rutherford's model could not explain why the orbiting electrons do not fall into the nucleus. According to classical physics, a charged particle moving in a circular path is accelerating and must keep radiating energy.

Guttation is the loss of water in the form of liquid droplets from the edges and tips of leaves. Guttation happens mostly at night or early in the morning, when the soil is moist and the air is humid, so transpiration is slow.

In dinitrogen pentoxide, nitrogen has an oxidation state of +5, the highest it can reach, because a nitrogen atom has five electrons in its outer shell.

The slightest push makes the ball fall off and it does not come back. A body is in unstable equilibrium when a small displacement lowers its centre of gravity, so the forces acting on it move it further away instead of back.

Ferric chloride is a salt of a weak base, iron(III) hydroxide, and a strong acid, hydrochloric acid, so its solution is acidic and has a pH below 7.

A pearl is built up from layers of nacre, which is mostly calcium carbonate held together by a protein called conchiolin.

Borax is sodium tetraborate decahydrate, Na2B4O7·10H2O, so it contains only sodium, boron, oxygen and hydrogen. Its chemical name is sodium tetraborate, and the ten molecules of water of crystallisation supply the hydrogen and part of the oxygen.

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.

In many single-celled organisms such as Amoeba and Paramecium, a special contractile vacuole collects excess water and some wastes from the cytoplasm and pumps them out of the cell.

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 opening of the pulmonary artery from the right ventricle is guarded by the pulmonary semilunar valve, which stops blood from flowing back into the ventricle when it relaxes.

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

Insulin lets glucose leave the blood and enter body cells, especially muscle and fat cells, and so it lowers the blood sugar level.

Vegetables and fruits supply most of the vitamins and minerals in a vegetarian diet, which is why they are called protective foods.

The radicle is the embryonic root, and it is the first part to come out of a germinating seed, growing downward to form the primary root.

Denisovans were an archaic group of humans, close relatives of the Neanderthals, first identified in 2010 from a finger bone found in Denisova Cave in the Altai Mountains of Siberia.