Which statement is true of a reversible reaction at equilibrium? athe concentration of reactants is less than the concentration of products. b the concentration of reactants and the concentration of products are equal. c the concentration of reactants is greater than the concentration of products. d the concentration of reactants and the concentration of products are constant. ethe concentration of reactants is decreasing and the concentration of products is increasing.

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.