Rock & Volcano

Total Questions: 33

1. Regarding sedimentary rocks which of the following statements is true? [39th B.P.S.C. (Pre) 1994]

(a) These are such rocks whose structure depend on temperature and pressure
(b) These rocks are crystal
(c) These rocks are deposited in layers
(d) These rocks cannot be formed in water

Correct Answer: (c) These rocks are deposited in layers

Solution:Sedimentary rocks are formed by the accumulation of sediments. This sediment or debris accumulates in low lying areas like-lakes. These sedimentary materials may be formed from eroded fragments of other or pre-existing rocks or even from the remains of plants or animals and fossils, most frequently found in sedimentary rocks, which comes in layers, called Strata. Thus all of the given statements are true related to sedimentary rocks.

2. Sandstone is flaky rock, because - [M.P.P.C.S. (Pre) 1993]

(a) It is formed in the desert
(b) It is formed due to Heat
(c) It is formed underwater
(d) It is formed on the mountain

Correct Answer: (c) It is formed underwater

Solution:Sandstone is a sedimentary rock composed of sand-sized grains of mineral, rock or organic materials. The sandstone forms under the sea or in low-lying areas. It converts into Quartzite, which is typically the most abundant type of sand grain present in sandstone. Chert, Conglomerate, Flints, etc. are some important types of sedimentary rock.

3. Which statement of the following is true for igneous rocks? [40th B.P.S.C. (Pre) 1995]

(a) These have little fossils
(b) They have porous for water
(c) They are both crystal and non-crystal
(d) These rocks have no silicas

Correct Answer: (c) They are both crystal and non-crystal

Solution:The origin of igneous rocks is mainly related to the process of a volcanic eruption. These types of rocks are formed by the cooling and solidification of material called Magma or Lava. Igneous rocks have both, crystalline and non-crystalline structure and thus Statement given in option (c) is true but all other given statements are wrong because these rocks are composed of silicate minerals and fossils and layers are not found in these types of rocks and also water supply through igneous rocks is very low.

4. Which of the following rocks is not likely to contain fossils? [Jharkhand P.C.S. (Pre) 2013]

(a) Conglomerate
(b) Granite
(c) Shale
(d) Sandstone

Correct Answer: (b) Granite

Solution:Among the given options, granite does not contain fossils. Granite is formed of magma from a volcanic eruption. It is example of Plutonic or Intrusive rocks. Conglomerate, sandstone and shale are examples of sedimentary rocks. Sedimentary rocks contain fossils.

Sedimentary rocks are often porous and allow water to pass through them. They are fossiliferous, meaning they contain fossils of plants and animals. They are stratified, meaning they are made up of many layers. They are often informative geological records, as they contain marks left behind by weather, wind, water, and biological activities

5. Origin of Metamorphic rocks occurs from ........ rock? [Jharkhand P.C.S. (Pre) 2011]

(a) Igneous
(b) Sedimentary
(c) Both Igneous and Sedimentary
(d) None of the above

Correct Answer: (c) Both Igneous and Sedimentary

Solution:"Metamorphism" is a Greek word which means "change of form". Metamorphic rock is a rock that has changed from one type of rock into another. As a result of intense heat from magma and pressure from tectonic shifting, these metamorphic rocks are produced from either Igneous rocks or Sedimentary rocks.

Rocks formed out of solidification of magma (molten rock below the surface) and lava (molten rock above the surface) and are known as igneous or primary rocks. Having their origin under conditions of high temperatures the igneous rocks are unfossiliferous. Granite, gabbro, basalt, are some of the examples of igneous rocks. There are three types of igneous rocks based on place and time taken in cooling of the molten matter, plutonic rocks, volcanic rocks and intermediate rocks. There are two types of rocks based on the presence of acid-forming radical, silicon, acidic rocks and basic rocks. Sedimentary rocks are formed by lithification consolidation and compaction of sediments. Hence, they are layered or stratified of varying thickness. Example: sandstone, shale etc. Sediments are a result of denudation (weathering and erosion) of all types of rocks. These types of rocks cover 75 per cent of the earth's crust but volumetrically occupy only 5 per cent (because they are available only in the upper part of the crust). Ice deposited sedimentary rocks are called till or tillite. Wind-deposited sediments are called loess.

6. Which one of the following is not associated with the 'group'? [Uttarakhand P.C.S. (Pre) 2012]

(a) Gneiss
(b) Sandstone
(c) Limestone
(d) Shale

Correct Answer: (a) Gneiss

Solution:In the given options Limestone, Sandstone and shale belong to sedimentary rocks, while Gneiss is an example of metamorphic rock. Normally Gneiss is formed by granite. Gneiss is a coarse-grained, banded metamorphic rock formed from intense heat and pressure on pre-existing igneous or sedimentary rocks, often featuring distinct bands of minerals like quartz, feldspar, and mica.

7. Which of the following is a Basic landform? [Uttarakhand P.C.S. (Pre) 2016]

(a) Volcanic cone
(b) Residual mountain
(c) Monadnock
(d) Erosional waterfall

Correct Answer: (a) Volcanic cone

Solution:

In the given option a Volcanic cone is a basic landform. It is formed as a result of the deposition of lava in a cone around the hole after a volcanic eruption. Significantly residual mountains are that type of mountains in their original form, which remain as residual mountains after being eroded. Similarly, erosional waterfalls are also the product of erosion monadnocks are eroded parts of rocks.

8. The most abundant gas emitted from volcanoes is - [Jharkhand P.C.S. (Pre) 2013]

(a) Water Vapour
(b) Helium
(c) Sulphur Dioxide
(d) Carbon Dioxide

Correct Answer: (a) Water Vapour

Solution:

The most abundant volcanic gas is water vapour (H₂O). Carbon dioxide (CO₂) and Sulphur dioxide (SO₂) are two other important gases present in a volcanic eruption. A significant amount of Hydrogen sulphide (H₂S), Hydrogen (H₂), Carbon mono oxide (CO), Hydrogen chloride (HCl), Hydrogen fluoride (HF) and Helium (He) gas is also found in it

9. Which one of the following is the highest volcanic mountain in the world? [U.P.P.C.S. (Pre) 2015]

(a) Mount Pinatubo
(b) Mount Kilimanjaro
(c) Mount Tall
(d) Mount Cotopaxi

Correct Answer: (d) Mount Cotopaxi

Solution:The highest volcanic mountain of the World in the given option is Mount Cotopaxi with its height of 5911 mt. The height of Mount Pinatubo is 1486 mt and Mount Kilimanjaro (5881 mt). Mount Tall (311 mt.) is located in Philippines. Mount Cotopaxi, an active stratovolcano in the Andes Mountains of Ecuador, is a significant feature in the Pacific Ring of Fire, known for its symmetrical cone and equatorial glaciers, and is the second-highest peak in Ecuador.

10. In which belt, the volcanic eruption is maximum? [M.P. P.C.S. (Pre) 2021]

(a) Mid Continental
(b) Circumpacific
(c) Mid Atlantic
(d) Intraplates Volcanoes

Correct Answer: (b) Circumpacific

Solution:Volcanic eruption is highest in the Pacific Ocean belt. About 75 percent of active volcanoes on earth are located in the pacific Ocean belt (known as the 'Ring of Fire') and most earthquakes in the world also occur in this region. The Ring of Fire is stretched to approximately 40,000 kilometers (24,900 miles) tracing boundaries between several tectonic plates including the Pacific, Juan de Fuca, Cocos, Indian-Australian, Nazca, North American, and Philippine Plates. The chain runs up along the western coast of South and North America, crosses over the Aleutian Islands in Alaska, runs down the eastern coast of Asia past New Zealand and into the northern coast of Antarctica. Bolivia, Chile, Ecuador, Peru, Costa Rica, Guatemala, Mexico, United States, Canada, Russia, Japan, Philippines, Australia, Papua New Guinea, Indonesia, New Zealand, and Antarctica are some of the important places located in the ring of the fire.

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