Final answer:
The situation where Danny observes the snowball undergoing a physical change is when he melts the snowball in his hands, as melting is a physical change where the state changes but the composition remains the same.
Step-by-step explanation:
The student has asked which of the situations described Danny observing an object undergoing a physical change. Among the options given:
- Danny throws the snowball against the wall.
- Danny melts the snowball in his hands.
- Danny drops the snowball on the ground.
- Danny rolls the snowball down a hill.
- Danny throws the snowball into a lake.
The correct answer is B. Danny melts the snowball in his hands. This is because melting is an example of a physical change. A physical change is a change to a sample of matter in which some properties of the material may change, but the identity of the matter does not. For example, when the snowball melts, it changes from a solid state to a liquid state, but the composition of the water remains the same, just in a different form.