Which one of the following is an example of Salt-Crystal growth ?
- A.Chemical weathering
- B.Physical weathering
- C.Biological weathering
- D.Bio-chemical weathering
Correct answer
Explanation
The correct answer is B, Physical weathering. When salt crystals grow inside the pores and cracks of a rock, they push the grains apart and break the rock mechanically, without changing its minerals. Salt weathering is common in hot deserts and along coasts. Water carrying dissolved salts seeps into a rock; as the water evaporates in the heat, salts such as sodium chloride, gypsum and calcium sulphate crystallise. The growing crystals, and their swelling when heated or wetted again, exert pressure strong enough to loosen grains and flake off the surface, much like ice in frost wedging. Sandstones with many pores are especially affected and often show honeycomb-like hollows. Option A is wrong because chemical weathering changes the rock's minerals through processes such as oxidation, carbonation and hydration. Option C is wrong because biological weathering is caused by living things, such as roots, burrowing animals and lichens. Option D is wrong because bio-chemical weathering is the chemical action of organisms, such as acids released by decaying matter. Exam tip: frost wedging, salt crystal growth and exfoliation are physical weathering.
Practice Questions
View allWhich one of the following is not a minor plate ?
- A.Cocos Plate
- B.Nazca Plate
- C.Caroline Plate
- D.Antarctic Plate
Show answer
The Antarctic Plate, carrying Antarctica and the ocean around it, is one of the seven major lithospheric plates. Plate tectonics divides the lithosphere into seven major plates and several minor ones.
Read the full explanation →Which of the following statements with reference to shadow zones in an event of an earthquake is/are correct ? 1. Zone between 105° and 145° from epicentre was identified as the shadow zone for both P-waves and S-waves 2. The shadow zone of P-waves is much larger than that of the S-waves Select the answer using the code given below:
- A.1 only
- B.2 only
- C.Both 1 and 2
- D.Neither 1 nor 2
Show answer
The band between 105° and 145° from the epicentre receives neither P-waves nor S-waves, but it is the S-wave shadow zone that is much larger, so statement 2 is wrong.
Read the full explanation →Which of the following statements about Ring of Fire is/are correct ? 1. It is a zone of convergence plate boundaries 2. It is an active seismic and volcanic zone 3. It is associated with deep trench Select the correct answer using the code given below :
- A.1 and 2 only
- B.2 and 3 only
- C.1 only
- D.1, 2 and 3
Show answer
The Ring of Fire around the Pacific is a belt of convergent plate boundaries, full of active volcanoes and earthquakes and lined by deep ocean trenches.
Read the full explanation →Which one of the following rivers is not a tributary of river Brahmaputra ?
- A.River Manas
- B.River Kameng
- C.River Mahananda
- D.River Subansiri
Show answer
The Mahananda rises in the Darjeeling hills, flows through north Bengal and Bihar and joins the Ganga, not the Brahmaputra.
Read the full explanation →Which of the following statements regarding tropical cyclones is/are correct ? 1. These storms develop during the summer and autumn in every tropical ocean except the South Atlantic and eastern South Pacific Oceans. 2. Tropical cyclones that occur in the North Atlantic and eastern North Pacific Oceans are known as typhoons. 3. Tropical cyclones that occur in the Indian and South Pacific Oceans are called cyclones. Select the answer using the code given below :
- A.3 only
- B.1 and 2 only
- C.1 and 3 only
- D.1, 2 and 3
Show answer
Tropical cyclones of the North Atlantic and eastern North Pacific are called hurricanes, not typhoons, so statement 2 is wrong.
Read the full explanation →