The formula of a compound represents:

1. an atom
2. a molecule
3. an ion
4. all of these

The symbol of sulphite ion is:

1. SO₄^2-
2. HSO₄^-
3. SO₃^2-
4. S^2-

Which of the following has zero valency?

1. Hydrogen
2. Chlorine
3. Carbon
4. Neon

The valencies shown by copper is:

1. 1 and 2
2. 2 and 3
3. 2 and 4
4. 1 and 3