IAS Prelims Exam: Physical Geography NCERT Questions: MINERALS AND ROCKS

For the Civil Services IAS Exam Geography has vast and it covers most sections of the General Studies for the IAS Prelims Exam. The geography is scientific in its orientation and hence the IAS Aspirants having Arts background find it very difficult to prepare the geography for the IAS Prelims Exam.

Q1. Consider the following statements regarding minerals found in earth crust.

1.The basic source of all minerals is the hot magma in the interior of the earth.
2.Minerals are always found in earth crust in combination with 2 or more elements.

Choose correct statements from the following codes

a. Only 1
b. Only 2
c. Both 1 and 2
d. Neither 1 nor 2

Answer: a

Explanation: Sometimes single element minerals like sulphur, copper, silver, gold, graphite are found.

Q2. Which of the following is/are properties of quartz?

1.It consists of silica
2.Insoluble in water.
3.used in radio and radar

Choose correct statements from the following codes

a. Only 1
b. Only 1 and 2
c. Only 2  and 3
d. 1,2 and 3

Answer: d

Explanation: It is one of the most important components of sand and granite. It consists of silica. It is a hard mineral virtually insoluble in water. It is white or colourless and used in radio and radar. It is one of the most important components of granite.

Q3. Consider the following statements

1.Half of the earth’s crust is composed of feldspar.
2.Pyroxene forms 10 per cent of the earth’s crust. It is commonly found in meteorites.
3.Mica is used in electrical instruments

Choose correct statements from the following codes

a. Only 1
b. Only 1 and 3
c. Only 2 and 3
d. 1, 2 and 3

Answer: d

Explanation: Mica forms 4 per cent of the earth’s crust. It is commonly found in igneous and metamorphic rocks.

Q4. Which of the following is/are true about igneous rocks?

1.Igneous rocks are classified based on texture.

2.The few examples of igneous rocks are Granite, quartzite and basalt.

3.Igneous rocks are formed by Intermediate conditions of cooling of molten magma.

Choose correct statements from the following codes

a. Only 1
b. Only 1 and 3
c. Only 2 and 3
d. 1, 2 and 3

Answer: b

Explanation: If molten material is cooled slowly at great depths, mineral grains may be very large. Sudden cooling (at the surface) results in small and smooth grains. Intermediate conditions of cooling would result in intermediate sizes of grains making up igneous rocks. Quartzite is metamorphic rock.

Q5. Consider the following statements regarding sedimentary rocks

1.In many sedimentary rocks, the layers of deposits retain their characteristics even after lithification.
2. Lithification is the process by which deposits through compaction turn into rocks.

Choose correct statements from the following codes

a. Only 1
b. Only 2
c. Both 1 and 2
d. Neither 1 nor 2

Answer: c

Explanation: In many sedimentary rocks, the layers of deposits retain their characteristics even after lithification. Hence, we see a number of layers of varying thickness in sedimentary rocks like sandstone, shale etc.

Q6.  With reference to metamorphism, which of the following is/are true?

1.    Metamorphism occurs when rocks are forced down to lower levels by tectonic processes
2.    When molten magma rising through the crust comes in contact with the crustal rocks
3.    When the underlying rocks are subjected to great amounts of pressure by overlying rocks.

Choose correct statements from the following codes

a. Only 3
b. Only 1 and 3
c. Only 2 and 3
d. 1, 2 and 3

Answer: d

Explanation: Metamorphism is a process by which already consolidated rocks undergo recrystallisation and reorganisation of materials within original rocks.

Q7. Consider the following statements and identify wrong statements

a. Metamorphism also occurs without original minerals within rocks undergo chemical changes.
b. Metamorphic rocks are not stratified.
c. Dark and light shades can be seen in metamorphic rocks
d. The crustal once formed may be carried down into the mantle (interior of the earth)

Answer: b

Explanation: Sometimes minerals or materials of different groups are arranged into alternating thin to thick layers appearing in light and dark shades. Such a structure in metamorphic rocks is called banding and rocks displaying banding are called banded rocks.

Q8. Consider the following statements

1. Mica is commonly found in sedimentary and metamorphic rocks.
2. Olivine often found in basaltic rocks is used in jewellery.

Select the correct answer from the following codes

a. Only 1
b. Only 2
c. Both 1 and 2
d. Neither 1 nor 2

Answer: b

Explanation:  Mica forms 4 per cent of the earth’s crust. It is commonly found in igneous and metamorphic rocks. Olivine is used in jewellery. It is usually a greenish crystal, often found in basaltic rocks.

Q9. Which of the following is/are organically formed sedimentary rocks?

1. chalk
2. limestone
3. shale

Select the correct answer from the following codes

a.Only 1
b.Only 1 and 2
c.Only 2 and 3
d. 1,2 and 3

Answer: b

Explanation: sedimentary rocks are classified into three major groups: mechanically formed — sandstone, conglomerate, limestone, shale, loess; organically formed— geyserites, chalk, limestone, and coal; chemically formed — chert, limestone, halite, potash.

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