Which of these represents a chemical change?

A) two compounds combining to form a mixture
B) a mixture being separated into two elements
C) a compound being separated into two elements
D) an element changing state from solid to liquid

the answer is C) A compound being separated into two elements.

Explanation A compound being separated into two elements is an example of a chemical change. A chemical change, by definition, new substances are formed. change of state is physical as is forming or separating a mixture

D) an element changing state from solid to liquid

A) Two compounds combining to form a mixture represents a chemical change.

To determine which option represents a chemical change, we need to understand the difference between physical changes and chemical changes.

Physical changes refer to changes where the substance's appearance or state is altered, but the chemical composition remains the same. Examples of physical changes include changes in state (e.g., from solid to liquid) or changes in shape or size.

On the other hand, chemical changes involve the rearrangement of atoms and result in the formation of new substances with different chemical properties. Examples of chemical changes include reactions that form new compounds or break down compounds into simpler substances.

Now, let's evaluate the options:

A) Two compounds combining to form a mixture: This represents a physical change because no new substances are formed. It's merely a mixing of compounds.

B) A mixture being separated into two elements: This also represents a physical change as the mixture is being physically separated into its components. No chemical reactions or formation of new substances occur.

C) A compound being separated into two elements: This represents a chemical change. When a compound is broken down into two elements, it involves a chemical reaction and the formation of new substances.

D) An element changing state from solid to liquid: This represents a physical change. The change in state does not alter the chemical composition of the element.

Based on our analysis, option C represents a chemical change - a compound being separated into two elements.

The word "compound" is a dead giveaway.