Based on the statements provided, here are the evaluations of their truthfulness:
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Burning campfire wood is a chemical change. - This statement is true. Burning wood involves a chemical reaction that produces ash, gases, and other compounds.
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Toasting marshmallows results in a chemical change. - This statement is also true. The process of toasting marshmallows causes them to undergo a chemical change due to the heat, which alters their structure and flavor.
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Burning campfire wood is a physical change. - This statement is false. As stated earlier, burning wood involves a chemical change.
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Toasting marshmallows results in a physical change only. - This statement is false because toasting marshmallows involves both physical and chemical changes.
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The heat produced by the fire chemically changes the surrounding air. - This statement is true. The heat can cause reactions in the air, such as altering gases and creating combustion byproducts.
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The heat produced by the fire physically changes the surrounding air. - This statement is also true. The heat from the fire can cause the air to expand and change temperature, which is a physical change.
In summary, the true statements are:
- Burning campfire wood is a chemical change.
- Toasting marshmallows results in a chemical change.
- The heat produced by the fire chemically changes the surrounding air.
- The heat produced by the fire physically changes the surrounding air.