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Daily Subjectwise Quiz Day 2 Geography II (Online Prelims Test)

1) Which of the following is/are correct about Mohorovicic Discontinuity?

  1. It is the boundary between the Earth’s crust and the mantle.
  2. The depth of Mohorovicic discontinuity is higher under the oceanic crust than it is under the continental crust.

Select the correct answer using the codes below:

  • a. 
  • b. 
  • c. 
  • d. 
Answer : a

Mohorovicic discontinuity

  • Moho, or Mohorovicic discontinuity is the boundary between the Earth’s crust and its mantle.
  • The Moho lies at a depth of about 22 mi (35 km) below continents and about 4.5 mi (7 km) beneath the oceanic crust.
  • Modern instruments have determined that the velocity of seismic waves increases rapidly at this boundary.

2) Consider the following statements with respect to Mica and Olivine 

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

Select the correct answer from the following codes

  • a. 
  • b. 
  • c. 
  • d. 
Answer : b

Mica & Olivine

  • Mica forms 4% 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.

3) Which of the following is/are correct about Earth’s Crust?

  1. About 98 percent of the total crust of the earth is composed of titanium, hydrogen, phosphorous, manganese, and sulphur.
  2. The oldest rocks on our planet are part of the continental crust.

Select the correct answer using the codes below:

  • a. 
  • b. 
  • c. 
  • d. 
Answer : b

Earth’s Crust

  • The most abundant elements in the Earth’s crust include oxygen, silicon, Aluminium, iron, and calcium.
  • All three rock types (igneous, sedimentary, and metamorphic) can be found in Earth’s crust.
  • The oldest rocks on our planet are part of the continental crust and date back approximately 4 billion years of age.
  • Ocean crust is constantly recycled through our planet’s system of plate tectonics and only dates back to approximately 200 million years ago.

4) Which of the following is/are correct about Igneous rocks?

  1. The Igneous rocks are formed by the cooling of molten magma and are classified based on texture.
  2. A few examples of igneous rocks are slate, marble, and quartzite.

Select the correct answer using the codes below:

  • a. 
  • b. 
  • c. 
  • d. 
Answer : a

Igneous rocks

  • If molten material is cooled slowly at great depths, mineral grains may be very large.
  • The sudden cooling (at the surface) results in small and smooth grains.
  • The Intermediate conditions of cooling would result in intermediate sizes of grains making up igneous rocks.
  • Granite, Pegmatite and basalt are examples of igneous rocks
  • Quartzite is not igneous rock it is metamorphic.

5) Consider the following statements with respect to Sedimentary Rocks?

  1. In many sedimentary rocks, the layers of deposits retain their characteristics even after lithification.
  2. Gypsum, shale, and sandstone are examples of Sedimentary rocks.

Which of the statement(s) given above is/are correct?

  • a. 
  • b. 
  • c. 
  • d. 
Answer : c

Sedimentary rocks

  • They 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).
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