Why do beryllium and calcium have similar chemical properties

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.

Identify the missing numbers below to show the result of multiplying the numbers (1.6 × 10-19)(5.0 × 106) = c × 10d

How many grams of aluminum will there be in 98g of al2o3?