Topaz crystals form in slowly cooling molten rock. Based on this information, which two statements are most likely true of topaz?
1 of 10 QUESTIONS
Topaz is distributed unevenly across Earth's crust.
Topaz could be found near an active volcano.
Topaz is likely to crystallize out of lake water.
Topaz must be grown under laboratory conditions.

Desertification refers to the conversion of a fertile region into a dry region similar to a desert. Desertification in Africa is moving at 5 km per year. The major causes include human activities which resulted in falling of trees and vegetation. The greenery decreased to satisfy the needs of fuel of the residing population. The other reason is the climate. The climate does not support agriculture or farming related activities. In view of the above discussed factors, desertification is estimated to gradually cover the whole of Africa in the future.