The original periodic table was useful because it could be used to predict properties of elements that had not yet been discovered.

Yes. But that was until a guy named Dmitri Mendeleev corrected the known atomic masses of some elements and used the patterns in his table to predict the properties of the elements he thought must have exist.

could you use this to with a topic?

the key difference between a democracy and a republic lies in the limits placed on government by the law, which has implications for minority rights. both forms of government tend to use a representational system — i.e., citizens vote to elect politicians to represent their interests and form the government.

your answer would be (b)