What is the depression at the top of a volcano following a volcanic eruption called?
- A.Chamber
- B.Vent
- C.Cinder
- D.Crater
Correct answer
Explanation
The correct answer is D, Crater. A crater is the bowl-shaped depression at the top of a volcano, around the opening through which lava, gas and ash come out.
During an eruption material is thrown out and the rim around the opening builds up, leaving a funnel-shaped hollow at the summit. When a very large eruption empties the magma chamber, the summit may collapse into a much wider depression called a caldera, often more than a kilometre across. Craters and calderas often fill with water to form lakes; Lonar in Maharashtra, though, is an impact crater made by a meteorite, not by a volcano.
A is wrong: the magma chamber is the reservoir of molten rock deep below the volcano, not a hollow at the top.
B is wrong: the vent is the opening or pipe through which magma reaches the surface; the crater is the depression around it.
C is wrong: cinders are small fragments of cooled lava thrown out in an eruption; they can pile up into a cinder cone.
Exam tip: magma chamber below, vent as the pipe, crater at the top, caldera when the summit collapses.
Practice Questions
View allWhich one of the following is a cold ocean current ?
- A.Brazilian Current
- B.Gulf Stream
- C.North Equatorial Current
- D.California Current
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It flows south along the west coast of North America, carrying cold water from higher latitudes towards the equator. As a rule, currents moving from the poles towards the equator are cold, and those moving from the equator towards the poles are warm.
Read the full explanation →Rani told her friends that last year she did boating in four different lakes, namely, Loktak, Barapani, Kolleru and Pulicat. Which of the following States did she visit?
- A.Manipur, Meghalaya, Kerala, Tamil Nadu
- B.Manipur, Meghalaya, Andhra Pradesh, Tamil Nadu
- C.Mizoram, Assam, Kerala, Tamil Nadu
- D.Mizoram, Assam, Andhra Pradesh, Tamil Nadu
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Loktak is in Manipur, Barapani in Meghalaya, Kolleru in Andhra Pradesh, and Pulicat on the Andhra Pradesh–Tamil Nadu border. Loktak is the largest freshwater lake in north-east India, famous for its floating islands of vegetation called phumdis; Keibul Lamjao, the only floating national park in the world, lies on it.
Read the full explanation →Consider the following statements on 'Fog' : 1. Fog is simply a cloud that forms close to the ground. 2. Radiation fog is associated with radiation cooling of the land at night. 3. Advection fog forms when moisture is blown over a cold surface and is chilled by contact. Which of the statements given above are correct ?
- A.1 and 2 only
- B.2 and 3 only
- C.1 and 3 only
- D.1, 2 and 3
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All three statements are correct descriptions of fog and its two main types. Fog forms when air near the ground cools to its dew point and its water vapour condenses on tiny dust and smoke particles, so it is in effect a cloud at or near ground level.
Read the full explanation →Salal Power Project is situated on which one among the following rivers?
- A.Chenab
- B.Jhelum
- C.Nubra
- D.Shyok
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The Salal hydroelectric project is a run-of-the-river project on the Chenab in the Reasi district of Jammu and Kashmir. Built and run by NHPC, Salal has an installed capacity of 690 MW and was the first project India built under the Indus Waters Treaty of 1960 on a western river.
Read the full explanation →India's territorial limit extends towards the sea up to
- A.10 nautical miles
- B.12 nautical miles
- C.14 nautical miles
- D.15 nautical miles
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India's territorial waters, where it has full sovereignty, extend 12 nautical miles (about 22.2 km) from the baseline of its coast.
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