Which one of the following karst landforms is the largest in size ?
- A.Polje
- B.Uvala
- C.Swallow Hole
- D.Sink Hole
Correct answer
Explanation
The correct answer is A, Polje. A polje is a very large, flat-floored depression in limestone country, often several kilometres long, far bigger than the other karst hollows.
Karst landforms develop where rainwater, made slightly acidic by carbon dioxide, dissolves limestone and dolomite. The name comes from the Karst region on the Adriatic coast of Slovenia and Croatia. Small funnel-shaped openings form first as swallow holes and sinkholes. When several sinkholes grow and join, they make a larger compound hollow called an uvala. The largest closed depressions are poljes, which may have their own streams, lakes and farmland on their floors.
B is wrong: an uvala is formed by sinkholes merging, so it is larger than them but much smaller than a polje.
C is wrong: a swallow hole is a small opening through which a surface stream disappears underground.
D is wrong: a sinkhole is a small funnel-shaped depression, usually a few metres to tens of metres across.
Exam tip: Size order of karst hollows: swallow hole/sinkhole < uvala < polje; stalactites hang from the roof, stalagmites rise from the floor.
Practice Questions
View allD performs her train journey by the shortest route from Bengaluru to New Delhi. Which one of the following rivers will she not cross while performing the journey?
- A.Narmada
- B.Yamuna
- C.Godavari
- D.Krishna
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The shortest rail route from Bengaluru reaches Delhi from the south through Agra and Mathura, which lie on the western side of the Yamuna, so the train never has to cross that river.
Read the full explanation →In India, the period of steady population growth refers to the decade(s) of:
- A.1981-2011
- B.1951-1981
- C.1921-1951
- D.1911-1921
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In the standard division of India's population history, the three decades from 1921 to 1951 are called the period of steady population growth.
Read the full explanation →Consider the following statements with reference to earthquakes:
1. Collapse earthquakes are most common.
2. Tsunamis are waves generated by the tremors and not an earthquake in itself.
3. High magnitude earthquakes i.e. 8+ are quite rare whereas 'tiny' types occur almost every minute.
Which of the statements given above are correct?
- A.1 and 2 only
- B.1 and 3 only
- C.2 and 3 only
- D.1, 2 and 3
Show answer
Statement 1 is false because tectonic earthquakes, not collapse earthquakes, are the most common type. Earthquakes are grouped by cause: tectonic (sliding of rocks along a fault), volcanic, collapse (the roofs of underground mines or caverns falling in), explosion (from nuclear or chemical blasts) and reservoir-induced.
Read the full explanation →With reference to earthquakes, which of the following statements are correct?
1. Earthquakes largely occur along the converging plate boundaries.
2. Point of origin of earthquake in lithosphere is known as focus/hypocentre.
3. Intensity of earthquake decreases with distance from the epicentre.
4. Epicentre of earthquake always remains over continents only.
Select the correct answer using the code given below.
- A.1 and 2 only
- B.1, 2 and 3
- C.2 and 3 only
- D.1 and 4
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The first three statements are true, while statement 4 is false because many earthquakes have their epicentre under the sea.
Read the full explanation →National Disaster Management Authority is headed by
- A.the Prime Minister.
- B.the Home Minister.
- C.the President.
- D.the Health Minister.
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Under the Disaster Management Act, 2005, the Prime Minister is the ex officio chairperson of the National Disaster Management Authority (NDMA).
Read the full explanation →