Every time materials undergo physical or chemical changes..a. a new substance is always formed. b. the total amount of matter always increases. c. the total amount of matter always decreases. d. the total amount of matter always remains the same.

Can someone me with questions 12 and 13 plz.

Nonpoint source pollution is difficult to control because it

How do temperature and salinity affect deepwater currents? as temperatures and salinity levels of water increase, the water rises to the surface where it creates currents as it moves to colder regions. they create changes in wind direction, moving denser water in the same direction as the wind and causing the deepwater circulation patterns found in the ocean. they equalize the forces on undersea currents caused by the coriolis effect as they replace more dense water with less dense water. they create density differences that cause dense deepwater currents to flow toward the equator where they displace less dense, warmer water above them.