World Geography Questions and Answers

Answer: C

Correct answer: The Moon passes between the Sun and the Earth

A solar eclipse happens when the Moon passes between the Sun and the Earth and casts its shadow on the surface, blocking the Sun from view along a narrow track. It is possible at all only because of a coincidence: the Sun is about 400 times wider than the Moon and also about 400 times further away, so the two appear almost exactly the same size in the sky. A solar eclipse can occur only at new moon, and a lunar eclipse - where the Earth’s shadow falls on the Moon, which is the second and fourth options combined - only at full moon. They do not happen every month because the Moon’s orbit is tilted about 5°, so it usually passes above or below the line. Totality is brief and its track narrow, which is why any given place sees a total solar eclipse only once in centuries, while a lunar eclipse is visible from the whole night side of the Earth at once.

Answer: A

Correct answer: Inter-Tropical Convergence Zone

The doldrums are the Inter-Tropical Convergence Zone, the belt near the equator where the northeast and southeast trade winds meet. Because the air there is converging and rising rather than blowing horizontally, surface winds are light and fitful - which is why sailing ships could be becalmed for weeks, and where the word doldrums in its ordinary sense comes from. The rising air produces heavy convectional rainfall and thunderstorms almost daily, and it is the reason equatorial regions are so wet. The zone migrates north and south with the overhead Sun, and its seasonal march is what brings the monsoon to India and the wet season to the Sahel. The horse latitudes are the calm belts near 30°, where air descends instead, producing the great deserts. The Roaring Forties are the strong westerlies of the southern ocean, and the polar front is where cold polar air meets warmer mid-latitude air.

Answer: A

All four are recognised air-mass types. Air masses are classified first by moisture source - maritime (m) or continental (c) - and then by the latitude of their source region: tropical (T), polar (P) or arctic (A).

Combining the two gives mT, mP, mA, cP and the other standard labels, so the option covering every listed type is correct.

Answer: A

The Bailadila hills of Chhattisgarh yield haematite, an iron oxide ore of very high grade - often above 65% iron - much of which is exported through Visakhapatnam.

Answer: D

Sima - silica plus magnesium - is the denser silicate material that makes up oceanic crust, so it is most abundant beneath the ocean floors. The lighter sial, silica plus aluminium, forms the continents.

Answer: C

The ozone layer is not pure ozone. It is a mixture of atomic oxygen (O), ordinary molecular oxygen (O₂) and ozone (O₃), all three interconverting continuously.

Ultraviolet light splits O₂ into two O atoms, each of which joins another O₂ to make O₃; ultraviolet then splits the O₃ again. It is this endless cycle that absorbs the harmful radiation.

Answer: C

Correct answer: The stratosphere

The stratosphere lies directly above the troposphere, separated from it by the tropopause, and extends to about 50 km. The order from the surface upward is troposphere, stratosphere, mesosphere, thermosphere, exosphere, and the temperature profile alternates: it falls with height in the troposphere, rises in the stratosphere, falls again in the mesosphere and rises in the thermosphere. The stratosphere warms with height because the ozone it contains absorbs ultraviolet radiation. That inversion - warm air above cool - makes the layer extremely stable, so there is almost no vertical mixing, which is why volcanic aerosols and pollutants injected into it can remain for years. It is also why aircraft cruise at its base: above the weather, in smooth air. The mesosphere above is the coldest part of the atmosphere and where meteors burn up.

Answer: A

The mean distance of the Earth from the Sun is about 149.5 million km, which the options give as 149,502,000 km. This distance is the astronomical unit.

Because the orbit is slightly elliptical the actual distance varies from about 147.1 million km at perihelion in early January to about 152.1 million km at aphelion in early July.

Answer: D

All three factors reduce infiltration as a storm goes on. Water fills the fine pores, so the capillary suction that first drew it in disappears; wetted clay particles swell and squeeze the pores narrower; and raindrop impact breaks the surface clods apart, washing fine particles into the remaining openings and sealing the surface.

The rate therefore falls steeply at first and then levels off at the soil's saturated permeability.

Answer: A

Correct answer: Rises to the surface without pumping, under natural pressure

An artesian well taps a confined aquifer - a permeable layer sandwiched between impermeable ones - whose recharge area lies at higher ground. The water in it is therefore under pressure, and when the confining layer is pierced the water rises of its own accord, sometimes flowing freely at the surface. Three conditions are required: a permeable aquifer, impermeable layers above and below, and the recharge zone at a greater elevation than the wellhead. The level to which the water would rise if unimpeded is the piezometric surface, and a well only flows freely if its top lies below that surface. The name comes from Artois in France, where such wells were drilled in the twelfth century. The Great Artesian Basin of Australia is the largest example, underlying a fifth of the continent and making pastoral use of the arid interior possible. An ordinary well in an unconfined aquifer has no such pressure and must be pumped.