Consider the following statements : Statement I : In the context of effect of water on rocks, chalk is known as a very permeable rock whereas clay is known as quite an impermeable or least permeable rock. Statement II : Chalk is porous and hence can absorb water. Statement III : Clay is not at all porous. Which one of the following is correct in respect of the above statements?
- A.Both Statement II and Statement III are correct and both of them explain Statement I
- B.Both Statement II and Statement III are correct but only one of them explains Statement I
- C.Only one of the Statements II and III is correct and that explains Statement I
- D.Neither Statement II nor Statement III is correct
Correct answer
Explanation
The correct answer is C, only one of Statements II and III is correct and that explains Statement I. Chalk is porous and lets water in, which explains why it is permeable; clay, however, is porous too, so Statement III is wrong.
Porosity is the share of empty space between grains; permeability is how easily water passes through those spaces. Chalk is a soft, white form of limestone made of the tiny shells of marine organisms, and its open pores and joints let water soak through, so chalk areas such as the downs of southern England have few surface streams. Clay has very high porosity and can hold a lot of water, but its pores are so tiny that water barely moves through them, so it is nearly impermeable. That is why clay layers form the base of aquifers and are used to line ponds and landfills.
A and B are wrong because both treat Statement III as correct.
D is wrong because Statement II is correct.
Exam tip: clay = porous but impermeable; chalk and sandstone = porous and permeable; granite = neither.
Practice Questions
View allIdentify the river of the Indian sub-continent on the basis of the following information :
1. It has an antecedent drainage system.
2. It flows through three countries.
3. It originates in the Tibetan Plateau and is an important river for irrigation.
4. It does not form distributaries.
Select the answer from the following :
- A.Brahmaputra
- B.Indus
- C.Sutlej
- D.Teesta
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The Sutlej is an antecedent river that rises in Tibet, flows through China, India and Pakistan, waters huge irrigated areas and, being a tributary, ends without forming a delta or distributaries.
Read the full explanation →Consider the following statements :
Statement I : In January, in the Northern Hemisphere, the isotherms bend equatorward while crossing the landmasses, and poleward while crossing the oceans.
Statement II : In January, the air over the oceans is warmer than that over the landmasses in the Northern Hemisphere.
Which one of the following is correct in respect of the above statements?
- A.Both Statement I and Statement II are correct and Statement II explains Statement I
- B.Both Statement I and Statement II are correct but Statement II does not explain Statement I
- C.Statement I is correct but Statement II is not correct
- D.Statement I is not correct but Statement II is correct
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In the northern winter the oceans stay warmer than the land, and that temperature contrast is what bends the isotherms.
Read the full explanation →At one of the places in India, if you stand on the seashore and watch the sea, you will find that the sea water recedes from the shore line a few kilometres and comes back to the shore, twice a day, and you can actually walk on the sea floor when the water recedes. This unique phenomenon is seen at
- A.Bhavnagar
- B.Bheemunipatnam
- C.Chandipur
- D.Nagapattinam
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At Chandipur beach in Balasore district of Odisha the sea pulls back several kilometres at low tide and returns at high tide, so visitors can walk on the exposed sea bed.
Read the full explanation →Consider the following statements :
Statement I : The amount of dust particles in the atmosphere is more in subtropical and temperate areas than in equatorial and polar regions.
Statement II : Subtropical and temperate areas have less dry winds.
Which one of the following is correct in respect of the above statements?
- A.Both Statement I and Statement II are correct and Statement II explains Statement I
- B.Both Statement I and Statement II are correct but Statement II does not explain Statement I
- C.Statement I is correct but Statement II is not correct
- D.Statement I is not correct but Statement II is correct
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Dust is indeed concentrated in subtropical and temperate belts, but the reason is that these belts have more dry winds, not less.
Read the full explanation →The process of Podsolization is predominantly found in:
- A.Equatorial forest
- B.Monsoon forest
- C.Taiga forest
- D.Mediterranean forest
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Podzolisation is the typical soil-forming process under the cool, moist coniferous forests of the taiga. In the taiga, cold winters slow down decay, and the needles of pine, spruce and fir form an acidic litter on the ground.
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