Geomorphology Questions and Answers

Answer: A

Only statement C describes meteoroids, so the answer is Only C.

Meteoroids are small pieces of rock that move around the Sun. Sometimes they come close to the Earth and tend to fall upon it; most burn up in the atmosphere as meteors.

Statements A and B describe asteroids, not meteoroids. The asteroid belt lies between the orbits of Mars and Jupiter, and scientists believe asteroids may be parts of a planet that broke up long ago. So the options naming A or B mix up the two kinds of body.

Answer: D

The horizons are C-horizon, A-horizon, B-horizon.

• X, small lumps of rock with cracks: the C-horizon, the layer of weathered parent rock just above the bedrock.
• Y, soft, porous and holding more water: the A-horizon or topsoil, rich in humus.
• Z, compact, rich in minerals but with less humus: the B-horizon, the middle layer.

Options listing top-soil or the A-horizon first put the descriptions in the wrong order, since X is clearly the rocky layer.

Answer: D

The moon moves around the earth in about 27 days.

The moon completes one revolution around the earth in about 27 days (27.3 days measured against the stars). It takes the same time to spin once on its axis, which is why we always see the same side of the moon from the earth.

The other figures are traps. About 29½ days is the time from one new moon to the next, which is longer because the earth has moved along its orbit around the sun in the meantime; 29 and 30 days come from that cycle or from the calendar month, and 28 days matches neither period. The question asks how long the moon takes to go around the earth, which is about 27 days.

Answer: C

The correct matching is (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii).

The Tropic of Cancer lies 23½° north of the Equator and the Tropic of Capricorn 23½° south of it. The Arctic Circle is 66½° north and the Antarctic Circle 66½° south.

The first option swaps both pairs of hemispheres, and the second and fourth mix up the tropics with the polar circles, so they are wrong.

Answer: C

The incorrect statement is Rotation is the movement of the earth around the sun.

Rotation is the spinning of the earth on its own axis, which takes about 24 hours and causes day and night. The movement of the earth around the sun in its orbit is revolution, which takes about 365¼ days and, with the tilt of the axis, causes the seasons.

The other three statements are correct. The earth is the third planet from the sun after Mercury and Venus. In size it is the fifth largest planet, after Jupiter, Saturn, Uranus and Neptune. Being slightly flattened at the poles and bulging at the Equator, its shape is described as a geoid.

Answer: A

Only Situation A is true.

The A-horizon (topsoil) and B-horizon (subsoil) hold the water, minerals and humus that roots use, so roots that grow and branch there absorb water and minerals well. Situation A is correct.

Situation B is false. The humus that makes soil soft and porous is in the topsoil, the A-horizon. The C-horizon is made of weathered and broken pieces of the parent rock, with little or no humus. So the options calling B true are wrong.

Answer: B

The bodies with their own heat and light are stars.

A star such as the sun produces heat and light through nuclear fusion in its core. The sun is the only star in our solar system and the source of its light and energy.

Planets and satellites have no light of their own: they shine because they reflect sunlight. Meteoroids are small rocky bodies that glow only briefly when they burn up in the atmosphere as meteors, which is friction heating, not their own light.

Answer: C

The keyed option is both (A) and (R) are correct and (R) explains (A).

Both statements come from the NCERT geography textbook's description of the lithosphere: the solid crust or hard top layer of the earth, made up of rocks and minerals and covered by a thin layer of soil. The key reads (R) as explaining (A) because it is the composition of rock and mineral that makes the lithosphere solid and hard.

Since both statements are true, the options saying either one is false are ruled out.

Answer: D

The two reasons are (b) and (d).

The NCERT geography textbook explains that when a river tumbles at a steep angle over very hard rocks, or down a steep valley side, it forms a waterfall. Hard rock resists erosion, so the river drops over it, and a steep valley gives the fall.

Trees along the bank have nothing to do with waterfalls. Soft rock is cut down evenly by the river and does not form a step; a waterfall typically forms where hard rock overlies softer rock that is worn away beneath it, but the hard rock is the reason given.

Answer: A

As we move away from the Sun, the time taken by planets to complete one orbit around the Sun increases.

A planet farther out travels a longer path and moves more slowly along it, so its year is longer. Mercury takes about 88 days, the Earth 365 days, Jupiter about 12 years and Neptune about 165 years.

The other options are wrong. Option B states the reverse. Size does not decrease steadily: the giants Jupiter and Saturn lie beyond the small rocky planets. And option D reverses the actual arrangement: the inner planets close to the Sun, Mercury to Mars, are rocky, while the outer planets are giants made mostly of gases and liquids.