Environmental Science
The earth's first atmosphere was composed primarily of:

Hydrogen and helium
Oxygen and water vapor
Carbon dioxide and water vapor
Argon and nitrogen

ANSWER DOWNLOAD EXAMIANS APP

Environmental Science
Which one is true?

commensalism when none of the interacting populations affect each other
commensalism when the interaction is useful to both the populations
symbiosis when the interaction is useful to both the populations
symbiosis when neither population affects each other

ANSWER DOWNLOAD EXAMIANS APP