The first inert gas to be isolated was argon, in 1894. Argon was found to have an atomic weight of slightly less than 40. Which of the following proposed changes to Mendeleev's original periodic table were supported by the properties of argon. I. Calcium should no longer be considered one of the alkaline earth metals

II. Another group of elements should be added to the periodic table.

III. The peridocity of elements should depend atomic number rather than atomic weight.