1. When 1.0 L of X2(g) (80 g/mol) is reacted with 3.0 L of Y2(g) (19 g/mol) at 760 torr and 273.15 K, 2.0 L of product was formed. Assuming all substances are gases, determine the formula of the product.

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.

it's filtration, but this is an assumption so my apologies if i got this

the electrical  conductivity  of asolution  of an electrolyte is measured by determining the resistance of thesolution  between two flat or cylindrical electrodes separated by a fixed distance.

where are the choice options?