Question

what do these two changes have in common?
an engine using gasoline to power a car
bleaching hair
select all that apply.
both conserve mass.
both are only physical changes.
both are chemical changes.
both are caused by cooling.

Explanation:

An engine using gasoline involves combustion (a chemical reaction converting gasoline to new substances like CO₂ and H₂O). Bleaching hair uses chemicals to break down melanin (a chemical change). Both are chemical changes. The law of conservation of mass applies to all chemical reactions, so mass is conserved in both. They are not physical changes (new substances form) nor caused by cooling.

Answer:

Both conserve mass., Both are chemical changes.