After about how many years of the formation of the earth, life appeared on this planet?

1. 500 billion years

2. 50 million years

3. 500 million years

4. 50 billion years

The concept of chemical evolution is based on 

1. crystallization of chemicals

2. interaction of water, air, and clay under intense heat

3. effect of solar radiation on chemicals

4. the possible origin of life by the combination of chemicals under suitable environmental conditions

Which of the following statements is TRUE?

1. Prokaryotes evolved before eukaryotes.
2. Eukaryotes evolved before prokaryotes.
3. Prokaryotes and eukaryotes evolved at approximately the same time.
4. It is unclear whether prokaryotes or eukaryotes evolved first