Sometimes you might not be able to see a new substance forming, so be on the lookout for evidence that a chemical change has occurred. A change in smell and color can indicate that a new substance has formed. For example, caramelized onions have a very different smell than raw onions. They have a darker color, too. Other physical properties about the onions change during caramelization, including their texture. The formation of bubbles can be evidence of a chemical change, but only if they indicate that a new gas is formed. If you heat a pot of water, the water will begin to boil. Those bubbles are not any new substance forming. They’re just the same water you started with changing state from liquid to gas.
Based on this passage, if you cannot see that a new substance has formed,
A
only a physical change could have occurred.
B
a chemical change might have occurred.
C
a change in state has always occurred.
D
no change could have occurred.
B
a chemical change might have occurred.