How do chemical weathering processes differ from mechanical weathering processes?

The answer is; Physical weathering does not change the composition of the rock while chemical weathering does.

Physical weathering only cracks and breaks the rocks into smaller pieces. Chemical weathering causes a reaction between the rock minerals and acidic rain or organic acids from plants forming different minerals or dissolving the rock minerals.  

he movement of air through earth's or any planet's atmosphere is called wind, and the main cause of earth's winds is uneven heating by the sun. this uneven heating causes changes of atmospheric pressure, and winds blow from regions with high pressure to those with low pressure.

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