Mass and energy are conserved: Question 3 options:

A)

only in physical changes.

B)

in chemical changes and physical changes.

C)

always in physical changes and sometimes in chemical changes.

D)

only in chemical changes.

Drug abuse will not lead to physical and psychological dependence. true or false ?

How does blood clotting prevent the entry of pathogens through cuts and wounds? answer asap,, this is due tomorrow. will mark as brainliest or whatever you call it : )

Nitric acid can be formed in two steps from the atmospheric gases nitrogen and oxygen, plus hydrogen prepared by reforming natural gas. in the first step, nitrogen and hydrogen react to form ammonia: (g) (g) (g) in the second step, ammonia and oxygen react to form nitric acid and water: (g) (g) (g) (g) calculate the net change in enthalpy for the formation of one mole of nitric acid from nitrogen, hydrogen and oxygen from these reactions. round your answer to the nearest .