Answer:
1. watershed
2. point
3. nonpoint
Explanation:
The land that supplies water to a river system is called a watershed
Pollution from a single, identifiable source is called point
Pollution that is difficult to link to a particular origin is called nonpoint
Physical changes occur when objects or substances undergo a change that does not change their chemical composition. This contrasts with the concept of chemical change in which the composition of a substance changes or one or more substances combine or break up to form new substances.
Friction <span>is most responsible for slowing a bicycle down when the brakes are applied</span>
