One hypothesis regarding earth's early atmosphere, includes this carbon-based gas along with ammonia, free hydrogen, and carbon dioxide

True

Explanation:

Earlier earth atmosphere was devoid of any oxygen gas, it was later when the evolution of cyanobacteria took place that gave off atmospheric oxygen as the earlier atmosphere was captured by solar nebula mostly of helium and hydrogen gases. Later on, the earth released volatile gases as the development of volcanicity. Hense a greenhouse rich atmosphere but poor in oxygen, as the earlier formation of air was these carbon-based gases and along with ammonia and free hydrogen. The atmosphere was nitrogen carbon and smaller amounts f gas.  Some models predict that the earth would have been made up of ice. carbon dioxide produced due to volcanic eruptions and methane due to organisms but got quickly destroyed by solar radiation some 4.4 Ga years ago.