250+ TOP MCQs on Geological Work of Atmosphere – 02 and Answers

Engineering Geology Interview Questions and Answers on “Geological Work of Atmosphere – 02”.

1. The main processes which does not come under chemical weathering are ____________
a) Solution
b) Hydration and hydrolysis
c) Insolation
d) Carbonation
Answer: c
Clarification: The processes, solution, hydration and hydrolysis, carbonation are all chemical processes and involve chemical reaction, whereas, insolation is a process of mechanical weathering.

2. The rock-mineral insoluble in water is ____________
a) Rock salt
b) Gypsum
c) Calcite
d) Pyrite
Answer: d
Clarification: Pyrite is insoluble in water, whereas, rock salt, gypsum and calcite are examples of minerals that are soluble in water to some extent.

3. Limestone is not easily soluble in pure water but carbonated water dissolves the rock effectively.
a) False
b) True
Answer: b
Clarification: Pure water is not a good solvent of minerals in most cases, but when the water is carbonated, its solvent action for many common minerals is enhanced. Thus, limestone is not easily soluble in pure water but carbonated water dissolves the rock effectively.

4. Minerals like Orthoclase and Felspar undergo which method of chemical decomposition?
a) Hydration
b) Hydrolysis
c) Oxidation
d) Reduction
Answer: b
Clarification: Ions may be exchanged whereby some ions from water may enter into the crystal lattice of the mineral. This process of exchange of ions is called hydrolysis. It is a very common process of weathering of silicate minerals and is best explained with reference to weathering of mineral Orthoclase, Felspar.

5. Which of the following is reduction?
a) Removal of hydrogen
b) Removal of electron
c) Removal of oxygen
d) Addition of oxygen
Answer: c
Clarification: Oxidation means of either removal of electron or hydrogen or addition of oxygen but, reduction may involve removal of oxygen or addition of hydrogen or electron.

6. 2KaISi₃O₈ + 2H₂O + CO₂ → Al₂Si₂O₅(OH)₄ + K₂CO₃ + 4SiO₂
Orthoclase + Carbonic acid → ___________ + Pot. Carbonate + Silica
Identify the mineral in the blank space of the equation.
a) Illite
b) Kaolinite
c) Montmorillonite
d) Halloysite
Answer: b
Clarification: The reaction of orthoclase with carbonic acid yields kaolinite {Al2Si2O5(OH)4 } and Pot. Carbonate and silica.

7. Which of the following about Spheroidal weathering is not true?
a) It is a complex type of weathering
b) Both mechanical and chemical weathering are believed to happen
c) Formation of joints is involved
d) Formation of joints is not involved
Answer: d
Clarification: Spheroidal weathering is a complex type of weathering observed in jointed rocks and characterized with the breaking of original rock mass into spheroidal blocks. Both mechanical and chemical weathering are believed to actively cooperate in causing spheroidal weathering. The original solid rock mass is split into small block masses by development of parallel joints.

8. Factor not affecting weathering is ____________
a) Colour of the rock
b) Nature of the rock
c) Climate
d) Physical environment
Answer: a
Clarification: Weathering is affected by the factors like nature of the rock, climate, physical environment but is not affected by colour of the rock. It has no influence over its weathering.

9. It is said that Sandstone is more resistant to weathering compared to Granite. What is the basic reason behind this phenomenon?
a) The external outline form of sandstone
b) Sandstone is harder than granite
c) Granite is mainly made of quartz
d) Sandstone is mainly made of quartz
Answer: d
Clarification: Among granite and sandstones exposed to atmosphere simultaneously in the same or adjoining areas having hot and humid climate, the sandstone will resist weathering to a great extent because they are made up mainly of quartz(SiO₂) which is highly weathering resistant mineral.

10. Identify the pair mismatched.
a) Cold and humid – Both mechanical and chemical weathering
b) Dry and cold – Neither of them
c) Hot and humid – Mechanical weathering is predominant
d) Hot and dry – Mechanical weathering is predominant
Answer: c
Clarification: In the hot and humid conditions chemical weathering is predominant and not mechanical, since, there is presence of moisture.

11. Which of the following rock forming minerals is more resistant to weathering compared to Hornblende?
a) Augite
b) Biotite
c) Olivine
d) Calcite
Answer: b
Clarification: The resistance to weathering increases in the following order for dark coloured minerals- Olivine, Augite, Hornblende, Biotite. Hence only Biotite is most resistant. Calcite as it is very reactive among the rock forming minerals.

12. Which of the following is true about Eluvium?
a) It is that category of end product of weathering that has been moved to some distance after its formation
b) It is associated with weathering of slopes
c) It is the end product of weathering that happens to lie over and above the parent rock
d) Regolith is not the other name for Eluvium
Answer: c
Clarification: The basic definition of Eluvium is “It is the end product of weathering that happens to lie over and above the parent rock”. Regolith is another term for eluvium.

13. The zone consisting of mixed composition is ____________
a) Zone A
b) Zone B
c) Zone C
d) Zone D
Answer: b
Clarification: Zone B is of mixed composition, partly of soil and partly of weathered rock, the latter becoming more dominating with depth.

14. Among the following the term which is not effect of chemical weathering is ____________
a) Scree formation
b) Disfiguring
c) Pitting
d) Honeycombing
Answer: a
Clarification: Disfiguring, pitting, honeycombing and loss of surface appearance are quite common effects chemical weathering on stones used irrationally without due regard to the local environment. Scree formation happens due to mechanical weathering.

15. Formation of colloids is sometimes the end product of weathering.
a) True
b) False
Answer: a
Clarification: The various process of chemical weathering operating on the rocks and minerals under different atmospheric conditions may not always end up in the formation of stable end products. Often they result in splitting of particles into smaller particles –the colloids- characterized by atoms with only partial satisfied electrical charges.