There are two different structural isomers for 2-butene. Single bonded carbon atoms allow for rotation around the C-C bond, however, placing a second bond (producing a double bond) between two carbon atoms stops the rotation around these atoms. How does this restriction of rotation give rise to two different structural isomers of 2-butene (cis/trans isomers). (Hint: consider cyclo compounds which also have cis/trans isomers.)

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.

answer; capital earns interest; entrepreneurship receives a profit or incurs a loss;