Question

What do these two changes have in common?

sauce burning on a stove
making paper from wood

Select all that apply.
A. Both are only physical changes.
B. Both are caused by heating.
C. Both are chemical changes.
D. Both are caused by cooling.

Answer 1

To define the commonality between two changes, we must assess whether they are physical or chemical. Physical changes do not alter the chemical composition of a substance, while chemical changes result in the formation of new substances with different properties.

Step-by-step explanation:

In comparing two changes to determine if they are physical or chemical changes, we look at the nature of the changes. A physical change affects the form of a chemical substance, but not its chemical composition. Examples of physical changes include freezing water to form ice, and cutting hair; neither of these processes changes the substances involved into new substances. In contrast, a chemical change involves a chemical reaction that converts substances into different ones, for instance, when burning wax or cooking bread dough in an oven, where new substances such as water and carbon dioxide are formed from wax, or the transformation of dough into bread with different properties than the original substances.

The commonality between the two changes depends on their specific nature. If both changes involve a substance remaining chemically the same and only its physical state or appearance is altered, then they are both physical changes. However, if new substances are generated as a result of the changes, with properties different from the starting materials, then both are chemical changes.