What does the prefix trans-indicate?

I think trans- prefix Definition of trans- (Entry 3 of 3) 1 : on or to the other side of : across : beyond transatlantic. 2a : beyond (a specified chemical element) in the periodic table transuranium

Explanation:

The prefix trans- and its variant tra-, which mean “across,” appear in many English vocabulary words, for example: transmit, transform, and trajectory. Consider the word translation, which is the carrying “across” from one language into another.

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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.