When were the key ingredients for life first present on Earth?
A. 4,000 years ago
B. 4 billion years ago
C. 4 million years ago
Answer: B
You might also like to view...
The lithosphere floats atop the
A. crust. B. mohorovicic. C. mantle. D. asthenosphere.
Black lung disease results from
A. Careless strip-mining methods B. The radioactivity around coal-fired power plants C. Coal dust literally filling lungs like dust in a vacuum cleaner bag D. The radioactivity in coal E. Coal dust causing inflammation and fibrosis in lungs
Electromagnetic energy travels in ____.
A. waves B. packets C. nodes D. modules E. chunks
Photosynthesis converts
A) light energy, carbon dioxide, and water into carbohydrates and oxygen. B) light energy, oxygen, and carbohydrates into carbon dioxide and water. C) heat energy, carbon dioxide, and water into carbohydrates and oxygen. D) heat energy, oxygen, and carbohydrates into carbon dioxide and water.