1. The smallest unit of an element is:
A. atom
B. molecule
C. compound
D. mixture

2. A molecule is made of:
A. atoms
B. cells
C. tissues
D. organs

3. The law of conservation of mass states that:
A. mass cannot be created or destroyed
B. mass can be destroyed
C. mass can be created
D. mass disappears

4. Dalton proposed:
A. atomic theory
B. cell theory
C. gravity law
D. motion law

5. Atoms combine to form:
A. molecules
B. elements
C. mixtures
D. gases

6. Water is a:
A. compound
B. element
C. mixture
D. metal

7. Oxygen molecule contains:
A. same atoms
B. different atoms
C. metals
D. compounds

8. Molecular mass is the sum of:
A. atomic masses
B. temperatures
C. volumes
D. densities

9. Mole represents:
A. fixed number of particles
B. weight
C. size
D. volume

10. Chemical formula shows:
A. composition of compound
B. color
C. smell
D. shape

11. Hydrogen is a:
A. element
B. compound
C. mixture
D. solution

12. Oxygen is a:
A. element
B. compound
C. mixture
D. solution

13. Carbon dioxide is a:
A. compound
B. element
C. mixture
D. metal

14. Atoms are:
A. extremely small
B. extremely large
C. visible easily
D. colorful

15. Molecules show:
A. properties of substance
B. color only
C. smell only
D. weight only

16. Atomic theory was proposed by:
A. Dalton
B. Newton
C. Einstein
D. Galileo

17. Mass is conserved in:
A. chemical reaction
B. melting
C. boiling
D. freezing

18. Molecules of elements contain:
A. same atoms
B. different atoms
C. metals only
D. gases only

19. Molecules of compounds contain:
A. different atoms
B. same atoms
C. metals only
D. gases only

20. Chemical formulas use:
A. symbols of elements
B. colors
C. shapes
D. sizes