With a ruler, draw a line that is 20 cm long. Divide the line into five, 4-cm segments. On a scale of each segment representing one billion years, label the following events in the history of Earth: a. formation of the earth
b. origin of life
c. evolution of photosynthesis
d. evolution of eukaryotes
e. evolution of multi-cellular life
f. the Cambrian explosion
g. first vertebrate land animals
h. evolution of dinosaurs
i. evolution of human beings

Solution:

The first traces of the life that existed on the earth can be traced back to about as old as 4.2 billion years. It indicates that life has evolved around 200 million years ago after the first appearance of the liquid water.

The origin of the life on earth is a natural process and is a series of evolution what we see today. Firstly earth was formed by dust and smoke particles and then different forms of life began to evolved on the earth.

The events of the evolution in the history of the earth is shown on the following number line below :

a and b

the water is warmed up by the sun and then it evaporates into the atmosphere. the sunlight warms the water by its heat. water is then cooled down and condensation takes place. the water then finally returns back to the earth by the process of precipitation in the form of rain or ice.

explanation: