Why are archaea in a separate domain from bacteria apex?

I believe this is because Archaea differ from bacteria in a number of ways. These includes;
Unlike bacteria, archaea cell walls do not contain peptidoglycan, Archaea have different membrane lipid bonding compared to Bacteria and Eucarya. That is Archaeal lipids lack the fatty acids found in Bacteria and Eukaryotes and instead have side chanis composed of repeating units of isoprene. Other differences are like Bacteria, Archaea have 70 S ribosomes, but they have a different shape; Archaea have more complex RNA polymerases than Bacteria, similar to Eucarya.

The answer to this will be from your lab notes/procedure. it would be best to ask another student who participated in the lab as we do not know what was done, what enzyme or if the temperature is celsius or fahrenheit. if i were to guess though i'd say the rate stopped due to enzyme denturing at high temperature

Ther are many reasons.. is it a multiple choice?