If nearly 79% of the atmosphere is made of nitrogen, why is it easier for organisms to obtain carbon dioxide than nitrogen?

The given statement is false.

Explanation:

The Precambrian era contains all of the time before 600 million years ago. The earth's history before the formation of the oldest rock with observable fossils in them refers to Precambrian era.

The discovery of sediments and other evidence implies the surface temperature of above 0° C during the early part of the Precambrian era.

Traces of hundreds of life forms are found in the microfossils of the Precambrian era. Some of these species were early photosynthesizers. Stromatolites are stratiform structures made from microorganisms, particularly blue-green algae.

So, the statement is false.