Questions

In biology, Homology is defined as any characteristic of biological organisms that is derived from a common ancestor. 

Hence, Homology is evidence of Common ancestry.

Radon gas is a source of natural groundwater pollution.

One atomic mass unit (AMU) is equal to the one-twelfth the mass of one carbon-12 atom.

When exports are greater than imports, net exports are positive and similarly, when imports are greater than exports, net exports are negative.

When a country imports goods, it buys them from foreign producers. The money spent on imports leaves the economy, and that decreases the importing nation's GDP.