What do these two changes have in common?
chicken cooking in an oven
bleaching hair
A: Both are chemical changes.
B: Both are only physical changes.
C: Both are caused by cooling.
D: Both are caused by heating.
Step 1: Think about each change.
Cooking chicken is a chemical change. The heat causes the matter in the chicken to change. Cooked chicken and raw chicken are different types of matter.
Bleaching hair is a chemical change. Hair contains colorful matter called pigment. The bleach reacts with the pigment and turns it into a different type of matter. The new matter gives the hair a lighter color than before.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Cooking is caused by heating. But bleaching hair is not.
Both are caused by cooling.
Neither change is caused by cooling.