Weathering: physical, chemical, and biological

Correct answer: B. Exogenic process

Correct answer: B, an exogenic process. Geomorphic processes are commonly grouped into endogenic and exogenic processes. Endogenic processes originate inside the Earth and include forces associated with internal heat, tectonic movement, and volcanism. Exogenic processes operate at or near the surface and are driven by agents such as water, wind, ice, temperature change, and organisms. Weathering breaks down or alters rock in place at the surface, so it belongs to the exogenic group. A is wrong because endogenic processes arise within the Earth. C is not the standard geomorphic classification for weathering. D is too narrow and refers to volcanic activity, which is generally linked with internal Earth processes, not ordinary surface weathering. Remember: “exo” means outside; surface processes are exogenic.

Correct answer: C. Generally it does not occur

Correct answer: C, generally it does not occur. Weathering is the breakdown, disintegration, or chemical alteration of rock at or near the place where the rock is found. The material normally remains in place after weathering. Transportation is a different step: running water, wind, glaciers, waves, or gravity carry the loosened material away. That carrying process is associated with erosion and movement, not with weathering itself. A is wrong because weathering does not always move material a long distance. B is wrong because weathering can occur on land and in many environments, not only in the sea. D is wrong because glaciers are only one possible transporting agent, and weathering is not limited to glacial regions. A useful warning is that weathering and erosion often work together, but they are not identical: weathering prepares the material, while erosion transports it.

Correct answer: D. Regolith

Regolith is loose material formed by weathering of rock. Exam tip: connect regolith with soil formation.

Correct answer: A. Rock breaks into smaller pieces

Physical weathering involves mechanical breaking. Exam tip: size changes but chemical composition does not.

Correct answer: B. Change in chemical composition of minerals

Chemical weathering can change the nature of minerals. Exam tip: treat composition change as the main sign.

Correct answer: C. Plant roots

Plant roots can grow in cracks and weaken rocks. Exam tip: connect activities of organisms with biological weathering.

Correct answer: D. By exerting pressure and widening cracks

Roots create pressure while growing and widen cracks. Exam tip: remember root pressure as a simple example.

Correct answer: A. Physical weathering

Direct answer: Option A, physical weathering. A temperature range means repeated heating and cooling. On heating, rock minerals expand; on cooling, they contract. Different minerals may expand by different amounts, and the outer surface may heat and cool faster than the interior. Repetition creates mechanical stress, cracks, and eventually the breaking or peeling of rock without requiring a chemical change. Option A is correct because this is mechanical disintegration. Option B is wrong because carbonation is chemical weathering involving carbonic acid, usually formed when carbon dioxide dissolves in water. Option C is wrong because hydrolysis is a chemical reaction between minerals and water. Option D is wrong because organic acid action involves acids produced by organisms or decaying matter and is chemical. Hot, dry areas often show strong thermal stress because daily temperature differences can be large, but the classification depends on the mechanical action. Memory cue: temperature changes break; they do not chemically transform—physical weathering.

Correct answer: B. Thermal physical weathering

Repeated heating and cooling can break rocks. Exam tip: connect daily temperature range with physical weathering.

Correct answer: C. Freezing and thawing of water in cracks

Water expands on freezing and exerts pressure on cracks. Exam tip: connect frost action with cold mountainous regions.

Correct answer: D. Because crystals grow and exert pressure

Salt crystals create pressure in cracks. Exam tip: remember salt weathering in coastal and arid regions.

Correct answer: A. Carbonic acid

Water and carbon dioxide form weak carbonic acid. Exam tip: connect carbonation with limestone.

Correct answer: B. Oxygen

In oxidation, oxygen reacts with minerals. Exam tip: remember rust-like colour in iron-bearing minerals.

Correct answer: C. Oxidation

Iron minerals can react with oxygen and form a rust-like colour. Exam tip: reddish-brown colour indicates oxidation.

Correct answer: D. It chemically changes them

In hydrolysis, water helps change minerals into new forms. Exam tip: understand it as chemical weathering.

Correct answer: A. They may absorb water and expand

In hydration, minerals may expand and weaken after taking water. Exam tip: remember water absorption.

Correct answer: B. Soluble minerals mixing in water

In solution, minerals dissolve in water and weaken rocks. Exam tip: treat it as a chemical weathering process.

Correct answer: C. Carbonation and solution

The direct answer is C, carbonation and solution. Limestone is mainly calcium carbonate. When rainwater absorbs carbon dioxide from the air and soil, it forms weak carbonic acid. Step by step: rainwater takes in carbon dioxide; weak carbonic acid forms; this acidic water enters cracks in limestone; calcium carbonate dissolves gradually; cracks may enlarge into caves, underground channels, sinkholes, and other karst features. Option C is correct because carbonation helps the water dissolve limestone, and solution is the actual dissolving process. Option A is wrong because earthquakes and tsunamis are sudden tectonic or marine hazards, not the usual chemical weathering processes that dissolve limestone. Option B is wrong because air pressure alone does not explain limestone dissolution. Option D is wrong because magma flow is a volcanic process and is not required for ordinary limestone weathering. Other processes can affect limestone, but C is the specific and complete pair here. Memory cue: limestone plus weak carbonic acid means carbonation and solution, often producing karst.

Correct answer: D. Because water helps chemical reactions

Moisture speeds up chemical reactions. Exam tip: connect hot and humid climate with chemical weathering.

Correct answer: A. Physical weathering

Direct answer: Option A, physical weathering. In cold regions, water enters cracks in rock. When it freezes, it expands and pushes the crack wider; when it thaws, more water can enter. Repeated freeze–thaw cycles eventually break the rock into pieces. This is mechanical action, so it is physical weathering, also called frost action or frost wedging. Option A is correct. Option B, carbonation, is chemical weathering in which carbonic acid in water reacts with minerals such as limestone. Option C, solution, is the chemical dissolving of soluble minerals in water. Option D, oxidation, is a chemical reaction commonly involving oxygen, such as rusting of iron-bearing minerals. Freezing and thawing may occur with chemical processes, but the described repeated expansion and cracking is physically mechanical. Memory cue: frost breaks; acids and oxygen chemically change.

Correct answer: B. They increase entry of water, air and roots

Cracks allow weathering agents to reach inside. Exam tip: remember joints and cracks as weak points.

Correct answer: C. Weathering may become faster

Weathering is the breakdown or alteration of rocks at or near Earth’s surface. When a rock is broken into smaller pieces, the total surface exposed to air, water, oxygen, acids, and living organisms becomes larger. More exposed surface gives these agents more places to act. As a result, chemical reactions and physical breakdown can proceed more rapidly, although the exact rate also depends on climate, rock type, moisture, temperature, and biological activity.

Option C is correct because an increase in surface area can make weathering faster. It does not mean that weathering must always speed up under every condition; it means the opportunity for weathering is greater. Option B is incorrect because surface area does affect contact with weathering agents. Options A and D are clearly wrong: weathering does not necessarily stop, and a rock does not immediately become a river. Thus, smaller fragments usually weather more readily than one solid block of the same material.

Correct answer: D. More quickly

Soft rocks may weaken faster due to lower resistance. Exam tip: connect rock hardness with weathering rate.

Correct answer: A. Parent material

Weathering changes rock into parent material from which soil forms. Exam tip: remember soil formation begins with weathering.

Correct answer: B. Lichen releasing acids

Lichens can release weak acids and alter rock surfaces. Exam tip: place lichens and mosses in biological weathering.