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which laboratory activities involve chemical changes? check all that apply.

leaving a copper penny in vinegar until it turns green
boiling saltwater for several minutes until only solid salt remains
extracting iron filings from a sand mixture using a magnet
crushing a rock with a hammer to extract mineral deposits
putting an iron nail outside for a month and observing changes

The correct activities are leaving a copper penny in vinegar until it turns green, and putting an iron nail outside for a month and observing changes.

Explanation:

The formation of the green component on the copper penny and the formation of rust on the iron nail when kept outside for a month are the illustrations of chemical changes. On the other hand, extracting fillings or iron from a sand mixture with a magnet, boiling salt water away, and crushing rock with a hammer are the illustrations of physical modifications.

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.

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