Question

how does chemical weathering occur?
plants, lichens, and mosses accelerating breakdown
due to physical factors such as freezing and thawing
by chemically breaking down rocks by water and gases

Explanation:

Chemical weathering is the breakdown of rocks through chemical reactions, not physical forces or biological action (the first option is biological weathering, the second is physical weathering). The correct option describes the core mechanism of chemical weathering: water and gases (like carbon dioxide, oxygen) react with minerals in rocks to alter their composition and break them down.

Answer:

by chemically breaking down rocks by water and gases