What are 3 common acids and their salts?

i know that hci-nacl is one but idk other ones

Smog is the term used to describe the combination of fog and smoke

Which substances have the lowest melting points: ionic covalent, or metallic

In the cathode ray tube experiment, j. j. thomson passed an electric current through different gases inside a cathode ray tube in the presence of an electric field. in which two ways did this experiment change scientists’ understanding of the atom?