1. What is the formula of water?

H_{2}O

2. What is the formula of sodium chloride?

NaCl

3. What is the formula of carbon dioxide?

CO2

4. The formula of magnesium chloride is MgCl_{2}. What is the ratio of magnesium ions to chloride ions?

1:2

5. The formula of sulfuric acid is H_{2}SO_{4}. How many atoms of each element are in the formula?

H = 2, S = 1, O = 4

6. The formula of calcium nitrate is Ca(NO_{3})_{2}. How many calcium, nitrogen and oxygen atoms are in the formula?

Ca = 1, N = 2, O = 6

7. There are two numbers alongside chlorine in the periodic table, 17 and 35.5. What does the number 17 represent?

atomic number

8. What does the number 35.5 represent?

relative atomic mass

9. Sodium chloride has the formula NaCl. The relative atomic mass of sodium is 23 and that of chlorine is 35.5. What is the relative formula mass of NaCl?

58.5

10. A water molecule has the formula H_{2}O. The relative atomic mass of hydrogen is 1 and that of oxygen is 16. What is the relative formula mass of a molecule of water?

18

11. What is the symbol for relative atomic mass?

Ar or RAM

12. What is the symbol for relative formula mass?

Mr or RFM

13. The relative atomic mass of hydrogen is 1. What is the relative formula mass of hydrogen molecules?

2

14. Sodium chloride has the formula NaCl; the relative atomic mass of sodium is 23 and that of chlorine is 35.5. What is the relative formula mass of NaCl?

58.5

15. A water molecule has the formula H_{2}O; the relative atomic mass of hydrogen is 1 and that of oxygen is 16. What is the relative formula mass of water?

18

16. A carbon dioxide molecule has the formula CO_{2}; the relative atomic mass of carbon is 12 and that of oxygen is 16. What is the relative formula mass of carbon dioxide?

44

17. What is the empirical formula of a compound with molecular formula C_{2}H_{4}?

CH_{2}

18. What is the empirical formula of a compound with molecular formula C_{3}H_{8}?

C_{3}H_{8}

19. A sample of magnesium carbonate was heated in an open test tube. Why did it lose mass?

gas/carbon dioxide escaped

20. 100 cm^{3} of a solution contained 2 g of salt. What is the concentration of the salt in g dm^{-3}?

20

21. A sample of copper carbonate was heated in an open test tube. Why did it lose mass?

gas/carbon dioxide escaped

22. Why does magnesium increase in mass when it is heated in air?

combines with oxygen

23. How many cm^{3} are there in 1 dm^{3}?

1000

24. What is 250 cm^{3} expressed in dm^{3}?

0.25

25. What is 0.5 dm^{3} expressed in cm^{3}?

500

26. 100 cm^{3} of a solution contains 1.5 g of salt. What is the concentration of the salt solution in g dm^{3}?

15

27. 250 cm^{3} of a solution contains 5 g of sugar. What is the concentration of the sugar solution in g dm^{3}?

20

28. A solution of copper sulfate has concentration 10 g dm^{3}. What mass of copper sulfate will be dissolved in 100 cm^{3} of solution?

1 g

29. 2 g of hydrogen reacts with oxygen to form 18 g of water. What mass of water will be formed from 1 g of hydrogen?

9 g

30. 2H_{2} + O_{2} → 2H_{2}O. How many molecules of hydrogen are needed to react with 1 dozen molecules of oxygen to form water?

2 dozen