What do these two changes have in common?
making jam
photosynthesis
A: Both are chemical changes.
B: Both are caused by cooling.
C: Both are only physical changes.
D: Both are caused by heating.
Step 1: Think about each change.
Making jam is a chemical change. It involves mixing fruit, sugar, and a substance called pectin.
When these ingredients are mixed and cooked, the chemical bonds in their molecules are broken. The atoms then link together to form different molecules that make up the jam.
Photosynthesis is a chemical change. Plants make sugar using carbon dioxide, water, and energy from sunlight.
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.
The reaction that makes jam is caused by heating. But photosynthesis is not.
Both are caused by cooling.
Neither change is caused by cooling.