When gaseous argon is allowed to diffuse , it separates into lighter and heavier fractions. What does this suggest about the nature of argon ?

May someone me with these science questions

Ants live on acacia trees in south america. the ants feed on sugars secreted by the trees. the trees provide room for the ants to live. the ants sting any other insect or animal that comes to eat the trees. what type of relationship is this?

To find the enthalpy of a reaction in the lab, you measured the of the reactants and the change during the reaction.