Which statement correctly distinguishes physical weathering from chemical weathering?

• A. Physical weathering involves chemical changes; chemical weathering does not.
• B. Physical weathering involves disintegration without chemical changes; chemical weathering involves chemical changes.
• C. Both processes involve chemical changes.
• D. Neither affects rocks.

Answer: (B)

The key idea here is whether the rock's minerals are chemically altered or not. Physical weathering breaks rocks into smaller pieces through mechanical forces like freeze–thaw, abrasion, or the expansion of roots, but the minerals themselves stay the same—there's no chemical change, just a change in size and shape. Chemical weathering, on the other hand, involves chemical reactions that transform minerals into new substances or dissolve them into solution, such as feldspar turning into clay minerals or calcite dissolving in acidic rain.

So the correct statement captures that contrast: physical weathering disintegrates rock without chemical changes, while chemical weathering involves chemical changes. The other options miss this distinction: one wrongly claims physical weathering involves chemical changes, another says both involve chemical changes, and another says neither affects rocks.