A mixture of gases contains 0.300 moles of argon gas and 0.700 moles of helium gas. The mixture is at constant temperature and has a total pressure of 0.350 atm. What is the partial pressure of each gas

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.

answerambulatory;