I need help with both are they right please read the questions my grades dropped and if I don’t get them up I can’t go out of town Friday please help me:( !

The density of an unknown gas at 98°c and 740 mmhg is 2.50 g/l. what is the molar mass of the gas with work showed?

Darla claims that the first periodic table developed by mendeleev was not completely accurate, so it is not useful at all. harmony argues that it establish the periodic table we use today, making it more credible. who is correct and why? darla is correct, because a model that has any mistakes should be thrown out. darla is correct, because a good model would not need to change. harmony is correct, because mendeleev’s model had all of the information correct in the first version. harmony is correct, because mendeleev’s model made predictions that came true.

Structure of the atoms: discovery of the nucleus in 1909i need answering all of these questions