What is the main problem associated with metal refining?

it is extremely dangerous.
it does not produce very much refined metal.
it generates a great deal of waste.
it uses up a great deal of energy.

Are produced in the light reactions and used in the calvin cycle. a)nadh and atp b)electrons and sugar c)nadt+ and adp d)sugar molecules

Hurry which of these is true about index fossils? a) are very scarcely found b) used as guides in relative dating c) found in the youngest layer of the rock d) used as reference points in absolute dating

Viruses can be transmitted through air, water, food, insect bites, and direct skin contact. once a virus gains entry into the body, it invades a host cell in order to? a. synthesize antibodies for defense b. deactivate the host cell's defenses c. access cell processes for reproduction d. metabolize host proteins and grow