[Solved] Source and Classification of Stones MCQs and Answers

1. The hot molten material occurring naturally below the surface of the Earth is called:

a) Lava

b) Slag

c) Magma

d) Tuff

Answer: c

Explanation: Hot molten material is called Lava when it erupts from a volcano and reaches the surface. Slag is waste material from the smelting of ore. Tuff is a porous rock formed by a consolidation of volcanic ash.

2. At what depth and rate is a hypabyssal rock formed?

a) Slow cooling of magma at considerable depth

b) Quick cooling of magma at a shallow depth

c) Rapid cooling of magma at Earth’s surface

d) Rapid cooling of magma at a shallow depth

Answer: b

Explanation: Plutonic rocks are formed by slow cooling of magma at considerable depth. Volcanic rocks are formed near the surface of Earth by rapid cooling of magma. Hypabyssal rocks are formed at a quick rate of cooling of magma at considerably shallow depths.

3. What is a sedimentary deposit?

a) Weathered product remains at site

b) Weathered product carried away in solution

c) Weathered product gets carried away agents

d) Insoluble weathered product is carried away in suspension

Answer: d

Explanation: Weathered product remains at site is called residual deposit. Weathered product carried away in solution is chemical deposit and Weathered product gets carried away agents is organic deposit.

4. Which factor disturbs the equilibrium of rocks, commencing metamorphism?

a) Increase in temperature

b) Decrease in temperature and pressure

c) Increase in temperature and pressure

d) Decrease in pressure

Answer: c

Explanation: Rocks are stable at a temperature below 200°C and at the pressure existing. Any increase in above two factors can initiate the process of metamorphism. One factor alone is not sufficient to start metamorphism.

5. Which of the following is not a metamorphic change?

a) Calcite to schist

b) Limestone to marble

c) Shale to slate

d) Granite to gneisses

Answer: a

Explanation: Calcite is a carbonate mineral whereas schist is a metamorphic rock formed by metamorphosis of mudstone/shale to the higher degree than slate.

6. Which of the following rocks are hard and durable?

a) Argillaceous rocks

b) Siliceous rocks

c) Calcareous rocks

d) Carbonaceous rocks

Answer: b

Explanation: Silica predominates in siliceous rock and is less affected by weathering and hence are hard and durable compared to argillaceous (clay), calcareous (calcium carbonate) or carbonaceous (carbon).

7. Foliated structure is very common in case of:

a) Sedimentary rocks

b) Plutonic rocks

c) Igneous rocks

d) Metamorphic rocks

Answer: d

Explanation: Foliated rocks can split up into layers along a definite direction only. Sedimentary rocks are generally stratified and igneous rocks are unstratified.

8. Granite is a type of:

a) Plutonic rock

b) Metamorphic rock

c) Hypabyssal rock

d) Volcanic rock

Answer: a

Explanation: Granite is formed at a slow rate of cooling of magma at considerable depths and so is a type of plutonic rock.

9. Stones are obtained from rocks that are made up of:

a) Ores

b) Minerals

c) Chemical compounds

d) Crystals

Answer: b

Explanation: Rocks are made up of minerals. They can be monomineralic (single mineral) or polymineralic (more than one mineral).

10. Which one of the following is not a classification of stones?

a) Physical Classification

b) Mineralogical Classification

c) Chemical Classification

d) Practical Classification

Answer: b

Explanation: The classifications of stones are physical (based on structure), chemical (based on chemical composition), practical (based on usage) and geological (based on the mode of origin). Mineralogical classification is not a means of classifying stones in general. It’s called chemical classification.