Consider the following statements about the sedimentary rocks:
Sedimentary rocks are formed at the earth's surface by the hydrological system
The formation of sedimentary rocks involves the weathering of preexisting rocks
Sedimentary rocks contain fossils
Sedimentary rocks typically occur in layers
Which of these statements are correct?
Correct Answer:
(D)
1, 2, 3 and 4
Sedimentary rocks are formed by the accumulation of sediments. This sediment or debris accumulates in low lying areas like-lakes. The Ocean is largely responsible for transporting sediment to locations where it accumulates. 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.
Ques: 2
Sandstone is flaky rock, because –
Correct Answer:
(C) It is formed underwater
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 quartz, which is typically the most abundant type of sand grain present in sandstone. Chert, Conglomerate, Flints, Silt etc. are some important types of sedimentary rock.
Ques: 3
Which statement of the following is true for igneous rocks?
Correct Answer:
(C) They are both crystal and non-crystal
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, fossils and layers are not found in these types of rocks and also water supply through igneous rocks is very low.
Ques: 4
Which of the following rocks is not likely to contain fossils?
Correct Answer:
(B) Granite
Among the given options, granite does not contain fossils. Granite is formed of magma from a volcanic eruption. Conglomerate, sandstone and shale are examples of sedimentary rocks. Sedimentary rocks contain fossils.
Ques: 5
Origin of Metamorphic rocks occurs from which rock ?
Correct Answer:
(C) Both Igneous and Sedimentary
"Metamorphic" is a Greek word which means "of changing 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.
Ques: 6
Which one of the following is not an example of Metamorphic rock ?
Correct Answer:
(D)
Granite
Granite is not an example of Metamorphic rock. It is an Igneous rock. The examples of Metamorphic rocks formed through Igneous rocks are as follows –
(1) Granite - Gneiss
(2) Basalt - Amphibolite
(3) Basalt - Schist
Marble is an example of metamorphic rock formed by sedimentary rock. The other examples of Metamorphic rocks formed through Sedimentary rock are as follows-
(1) Shale - Slate
(2) Limestone - Marble
(3) Chalk and dolomite - Marble
(4) Sandstone – Quartzite
Ques: 7
Which one of the following is not associated with the 'group'?
Correct Answer:
(A) Gneiss
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 but sometimes it is also formed by Gabbro or shale.
Ques: 8
Rock formed inside the Earth as a result of solidification of lava is called –
Correct Answer:
(A) Plutonic rocks
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.