Question

which of these are physical changes in matter? check all that apply. boiling water a pencil being sharpened exploding dynamite freezing water rotting cheese

Explanation:

• Boiling water: A physical change as it involves a change of state (liquid to gas) without altering the chemical composition of water ($H_2O$).
• A pencil being sharpened: A physical change as it only changes the shape and size of the pencil (wood and graphite), not its chemical nature.
• Freezing water: A physical change as it is a change of state (liquid to solid) of water ($H_2O$) without a chemical reaction.
• Exploding dynamite: A chemical change as it involves a chemical reaction (decomposition of dynamite compounds) to produce new substances (gases, etc.).
• Rotting cheese: A chemical change as it is a result of microbial action and chemical reactions that change the chemical composition of the cheese.

Answer:

boiling water, a pencil being sharpened, freezing water