Question

A sharp, irregularly shaped rock falls into a river. Over time, the edges of the rock become smooth and rounded by rubbing against other rocks. This is an example of _____.a. chemical weathering
b. biological weathering
c. physical weathering

Answer 1

Answer:

c. physical weathering

Explanation:

Physical weathering is a geological phenomenon that involves the disintegration of rocks into smaller constituent without a change in it chemical composition.  Agents of physical weathering could be water , temperature , wind and  plant growth or animal action.

In the case of this question, the agent of the physical weathering is water. The river carries this rock fragments rubbing the edges of the rocks to another to change the rock shape without altering it chemical composition   . The rocks are only modified by it changes in shape but it still retain it initial chemical composition. This process can be regarded as mechanical weathering .