World Geography Questions and Answers

Answer: B

The reaction of minerals with carbonate and bicarbonate ions is carbonation. Rainwater dissolves carbon dioxide to form weak carbonic acid, which attacks calcium carbonate and converts it into soluble calcium bicarbonate:

\[ \mathrm{CaCO_3 + H_2O + CO_2 \rightarrow Ca(HCO_3)_2} \]

This is the process that dissolves limestone and produces karst caves and sinkholes.

Answer: C

Dogger Bank, Rockall Bank and the other banks named lie in the north-east Atlantic, around the British Isles and the North Sea.

A bank is a shallow rise on the continental shelf. Sunlight reaches the bottom there and nutrients are stirred up, so plankton is abundant and these banks have been among Europe's richest fishing grounds for centuries.

Answer: A

Correct answer: A seismograph

A seismograph records ground motion. The classic design suspends a heavy mass that tends to stay still by inertia while the frame and the ground move beneath it, and the relative motion is traced onto a rotating drum or, now, recorded electronically. The trace itself is a seismogram. Readings from at least three separated stations locate an earthquake, by comparing the arrival times of the fast P waves and the slower S waves; the gap between them gives the distance to the source, and three distances fix the point. Note that magnitude is not an instrument but a scale computed from the record: the Richter scale, and now the more widely used moment magnitude scale, both logarithmic, so a step of one unit is roughly a thirtyfold increase in energy released. A barometer measures air pressure and a hygrometer humidity; neither has anything to do with earthquakes.

Answer: C

The Polar Easterlies blow between about 60° and 90° in each hemisphere, from the polar high towards the sub-polar low.

The Trade Winds occupy roughly 0–30° and the Westerlies roughly 30–60°. All three belts are deflected by the Coriolis force, which is why the polar winds arrive from the east.

Answer: C

The ionised layers of the upper atmosphere are dense enough to burn up falling meteorites by friction long before they reach the surface, which is why most are seen only as brief streaks of light.

Ultraviolet radiation is absorbed lower down, by the ozone layer in the stratosphere, and infrared is largely trapped by water vapour and carbon dioxide in the troposphere.

Answer: B

Correct answer: Oxygen

Oxygen makes up about 46 per cent of the crust by mass, more than every other element combined. Silicon follows at about 28 per cent, then aluminium at 8 and iron at 5. The result is surprising only if oxygen is thought of as a gas. In the crust it is locked into silicate minerals, whose building block is the \( \mathrm{SiO_4} \) tetrahedron - one silicon atom surrounded by four oxygens. Since silicates make up over 90 per cent of the crust, oxygen dominates by sheer arithmetic. The picture changes with depth. The Earth as a whole is mostly iron, because the core is iron and nickel; iron is the single most abundant element in the planet by mass. And it changes again on the largest scale: the universe is overwhelmingly hydrogen and helium, neither of which is abundant in the crust at all.

Answer: A

Correct answer: Brazil

Brazil covers about 8.5 million square kilometres, nearly half of South America, and is the fifth largest country in the world. It borders every South American country except Chile and Ecuador. It is also the only Portuguese-speaking country on the continent, a legacy of the Treaty of Tordesillas of 1494, which divided the newly encountered lands between Portugal and Spain along a meridian; the bulge of South America fell on the Portuguese side. Most of the Amazon basin and its rainforest lies within it, and its capital Brasília was built inland from nothing in the 1950s to draw settlement away from the coast. Argentina is the second largest South American country and the eighth largest in the world; Peru and Colombia follow well behind.

Answer: C

Correct answer: The northern hemisphere

The northern hemisphere holds roughly two thirds of the world’s land, and is about 60 per cent ocean; the southern is around 81 per cent ocean. Nearly 90 per cent of the world’s people live north of the equator. This asymmetry has a real climatic effect. Land heats and cools much faster than water, so the northern hemisphere has a larger annual temperature range and more pronounced continental climates, while the southern is moderated by its vast oceans. It is also why the thermal equator - the belt of highest temperature - sits north of the geographic one for most of the year. The monsoon system depends on the same contrast: the huge Asian landmass heating in summer draws air from the Indian Ocean. The eastern hemisphere does hold more land than the western, but that division is a separate one, made by the Prime Meridian rather than the equator.

Answer: C

Africa covers about 30,065,000 km², roughly a fifth of the world's land surface.

Only Asia is larger. Africa spans about 8,000 km from Tunisia to the Cape and straddles the equator, so it has the widest range of tropical climates of any continent.

Answer: C

Correct answer: Lake Baikal

Lake Baikal in southern Siberia reaches about 1,642 metres, making it the deepest lake in the world and the largest by volume - it holds roughly a fifth of all the unfrozen fresh water on the surface of the planet, more than all five North American Great Lakes together. Its depth comes from its origin: it lies in a continental rift, where the crust is pulling apart, so the basin is still deepening. It is also the oldest lake known, at about 25 million years, and that long isolation has produced a remarkable endemic fauna, including the world’s only exclusively freshwater seal. Lake Superior is the largest freshwater lake by surface area, and Lake Victoria the largest in Africa and the second largest by area, but both are comparatively shallow. The Caspian is the largest enclosed body of water on Earth, but it is saline and generally classed as a sea.