1. Piece of matter in pure form is called:

2. The sum of protons and neutrons in the nucleus of an atom is called:

3. A substance whose atoms have the same atomic number is called:

4. Which one of the followings is the mixture of oxygen, nitrogen and carbon dioxide?

5. Which one of the followings has sharp and fixed melting point?

6. The number of particles in one mole of a substance is called:

7. An atom or group of atoms having odd number of electrons is called:

8. The unique property of an element is called:

9. The sum of atomic masses of all the atoms in one formula unit of a substance is called:

10. An atom or group of atoms having positive charge on it is called: