Put these events in Earth history in order.
Oldest < second oldest < ... < youngest:

1. production of oxygen by photosynthetic organisms
2. rigin of eukaryotic cells
3. earliest evidence for life on Earth
4. appearance of first tetrapods on land surfaces
5. Cambrian "explosion"

Explanation:

The events of earth history from oldest to new are as follows:

Scientists assume that the Earth evolved about 4.6 billions years ago. However, the first evidence of life dates back to 3.7 billion years ago. It is assumed that the conditions of primitive Earth were such that it could not support life. However the inorganic compounds spontaneously reacted and gave rise to biological molecules such as amino acids, proteins lipids etc.In this way the first cells appeared as prokaryotes, photosynthetic prokaryotes began to produce oxygen and gradually new forms of life arose.

An important event in the history of Earth is cambrian explosion during which several forms of life arose and diversified to occupy various strata of Earth.