GEOLOGY

Detailed explanation-1: -Sinkholes form when limestone under a layer of sand is dissolved by rainwater. The ground above the limestone collapses into a hole when enough limestone dissolves.

Detailed explanation-2: -Limestone areas are predominantly affected by chemical weathering when rainwater, which contains a weak carbonic acid, reacts with limestone. This causes the limestone to dissolve.

Detailed explanation-3: -Chemical weathering is caused by rain water reacting with the mineral grains in rocks to form new minerals (clays) and soluble salts. These reactions occur particularly when the water is slightly acidic.

Detailed explanation-4: -Sulfur dioxide and nitrogen gases create other types of acid rain that act as chemical weathering agents. Some sources of sulfur dioxide are power plants that burn coal; as well as volcanoes and coastal marshes. Sulfur gases react with oxygen and rainwater to form sulfuric acid.

Detailed explanation-5: -Limestone is chemically weathered by a process of carbonation. As rainwater absorbs carbon dioxide as it passes through the atmosphere it becomes a weak carbonic acid. The water and carbon dioxide combine to form a weak carbonic acid.