List 3 accurate statements about russia

What is the amount of organic matter in all living organisms in a habitat called?

The caste system in india was used for what purpose? a) to ensure that all people had an adequate income b) to prevent the rich from taking too much power c) to provide social control and conformity according to one’s birth d) to draft a military capable of defending india from mongol invasion

What are the answers to numbers 7,10,12