Rock & Volcano

11. The molten material found inside the earth is called [Uttarakhand P.C.S. (Pre) 2006]

(a) Lava
(b) Basalt
(c) Obsidian
(d) None of the above

Correct Answer: (d) None of the above

Solution:Magma is a molten and semi-molten rock mixture found under the surface of Earth. Magma is a very fluid and dynamic substance having a temperature between 600° C to 1200° C. When Magma is ejected by a volcano, the material is called Lava. Magma on cooling converts into a solid known as igneous rocks. On the basis of silica's concentration lava is of two type (1) Acidic lava: It contains a large amount of Silica, highly viscous. (2) Basic lava: It contains a small amount of silica and is highly fluid.

12. Rock formed inside the Earth as a result of solidification of lava is called - [Uttarakhand P.C.S. (Pre) 2006]

(a) Plutonic rocks
(b) Volcanic rocks
(c) Metamorphic rocks
(d) Sedimentary rocks

Correct Answer: (a) Plutonic rocks

Solution:Igneous rock is formed by cooling and solidification of erupted magma. Internal Igneous rocks are of basically two types: (1) Plutonic rock (2) Hypabyssal (intermediary) rock. When Magma cools and solidifies below the Earth's surface at great depth the 'Plutonic rocks' are formed. As plutonic rocks are situated deep inside the ground, it takes much time to cool and hence their crystals are of larger size.

13. Volcanic eruptions do not occur in the: [I.A.S. (Pre) 2001]

(a) Baltic Sea
(b) Black Sea
(c) Caribbean Sea
(d) Caspian Sea

Correct Answer: (a) Baltic Sea

Solution:The volcanic eruption is related to Plate's edges in the convergence and divergence area. In the given option, the Baltic Sea is not related to plate's edge, thus, it is clear that the volcanic eruption does not occur in the Baltic Sea.

14. Mt. Etna is- [43rd B.P.S.C. (Pre) 1994]

(a) A mountain
(b) A mountain peak
(c) A volcano
(d) A plateau

Correct Answer: (c) A volcano

Solution:Mount Etna is an active volcano on the East-coast of Sicily, Italy. Its maximum height is about 3357 meter. It is sometimes referred to simply as Etna, is an active volcano on the east coast of Sicily, the largest island in the Mediterranean Sea. Etna's peak is the highest in Italy south of the Alps, and it is Europe's largest and one of the most active volcanoes. Etna's summit has five craters, which are responsible for most of the volcano's eruptions; there are also "flank" eruptions that occur out of 300-odd vents of varying sizes along the slopes of the mountain. It is in almost constant activity, and has seen, since the year 1600, at least 60 flank eruptions and many more summit eruptions. It has been a UNESCO World Heritage Site since 2013.

15. Where is the mount Saint Helens situated? [I.A.S. (Pre) 2005]

(a) Chile
(b) Japanese
(c) Philippines
(d) United State of America

Correct Answer: (d) United State of America

Solution:Mount Saint Helens is an active strato volcano located in Skamania county, Washington in the Pacific North West Region of United States of America. It is also known as the 'Fuji of America'. It is a volcanic peak in the Cascade Range of southwestern Washington, United States of America. It is part of the larger Pacific Ring of Fire. The volcano was formed during four eruptive stages beginning about 275,000 years ago and has been the most active volcano in the Cascade Range during the Holocene. Its eruption on May 18, 1980, was one of the greatest volcanic explosions ever recorded in North America.

16. Mauna Loa is an active volcano in - [U.P.P.C.S. (Mains) 2014, U.P.P.C.S. (Pre) 2005]

(a) France
(b) Hawaii
(c) Italy
(d) Japan

Correct Answer: (b) Hawaii

Solution:In Hawaiian language, Mauna Loa means the 'Long Mountain'. It is one of the active volcanoes. Mauna Loa had its first well documented eruption in 1843. It is spread over half of the Hawaii Island (USA). Mauna Loa is one of five volcanoes that together make up the Big Island of Hawaii, which is the southernmost island in the Hawaiian archipelago. It's not the tallest (that title goes to Mauna Kea) but it's the largest and makes up about half of the island's land mass. It sits immediately north of Kilauea volcano, which is currently erupting from its summit crater. Kilauea is well-known for a 2018 eruption that destroyed 700 homes and sent rivers of lava spreading across farms and into the ocean. Mauna Loa last erupted 38 years ago. In written history, dating to 1843, it's erupted 33 times.

17. Mauna Loa is an example of- [39th B.P.S.C. (Pre) 1994]

(a) Active volcano
(b) dormant volcano
(c) Dead volcano
(d) Plateau in the volcano region

Correct Answer: (a) Active volcano

Solution:In Hawaiian language, Mauna Loa means the 'Long Mountain'. It is one of the active volcanoes. Mauna Loa had its first well documented eruption in 1843. It is spread over half of the Hawaii Island (USA). Mauna Loa is one of five volcanoes that together make up the Big Island of Hawaii, which is the southernmost island in the Hawaiian archipelago. It's not the tallest (that title goes to Mauna Kea) but it's the largest and makes up about half of the island's land mass. It sits immediately north of Kilauea volcano, which is currently erupting from its summit crater. Kilauea is well-known for a 2018 eruption that destroyed 700 homes and sent rivers of lava spreading across farms and into the ocean. Mauna Loa last erupted 38 years ago. In written history, dating to 1843, it's erupted 33 times.

18. Which of the following is the World's largest volcano erupted for the first time in 38 years? [68th B.P.S.C. (Pre) 2022]

Correct Answer: (c) Mauna Loa

Solution:

The most active volcano in the world, Mauna Loa which is located in Hawaii (US), erupted in 2022, spewing ash and lighting up the sky with a red glow. Significantly the Hawai- ian name "Mauna Loa" means "Long Mountain". This name is fitting, because the subaerial (above sea level) part of the Volcano extends about 120 km from the southern trip of the island To the summit Caldera and then east-northeast to the coastline near itilo.

19. Which of the following are active volcanoes? [U.P.P.C.S. (Mains) 2007]

1. Aconcagua

2. Cotopaxi

3. Etna

4. Fujiyama

Select the correct answer from the code given below:

(a) 1 and 2
(b) 3 and 4
(c) 1, 2 and 3
(d) 2, 3 and 4

Correct Answer: (d) 2, 3 and 4

Solution:Cotopaxi, Etna and Fujiyama are active volcanoes while Aconcagua is a volcanic mountain but not active volcano. Aconcagua is in Argentina near its border with Chile. Cotapaxi is situated in Ecuador, Etna in Italy and Fujiyama in Japan.

20. Which of the following are active Volcanoes? [U.P.P.C.S. (Mains) 2011]

1. Aconcagua

2. Etna

3. Kilimanjaro

4. Vesuvius

Select the correct answer from the code given below

(a) 1 and 2
(b) 1 and 3
(c) 2 and 3
(d) 2 and 4

Correct Answer: (d) 2 and 4

Solution:Kilimanjaro is a dormant volcano situated in Tanzania and Aconcagua is a non-volcanic mountain. The other two are active volcanoes. Vesuvius is situated at (Naples), Etna in Sicily, Italy. Thus, option (d) 2 and 4 are correct.