What is the mass, in grams, of a sample that contains 4.05 x 1025 molecules?

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explanation: i will tell you how to if u answer my question.

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

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elements make up everything, and they combine to make compounds.

the answer is c