Calculations quiz

1. Work out the empirical formula of an oxide of chlorine contains 7.1 g of chlorine and 1.6 g of oxygen.

2. What is the atomic number of a beryllium atom?

3. A sample of bromine contained the two isotopes in the following proportions: bromine-79 = 50.7% and bromine-81 = 49.3%. Calculate the relative atomic mass of bromine

4. Calculate the relative formula mass(Mr) of a molecule of bromine (Br₂)

5. What is meant by the term molecular formula?

6. To determine the formula of a metal oxide by combustion, magnesium is heated in a crucible. Why is a lid lifted from time to time?

7. What are the three subatomic particles?

8. An oxide of nitrogen contains 26% nitrogen and 74% oxygen and has a relative molecular mass of 108. Find the empirical and molecular formulae for the oxide.

9. How many electrons can the first, second and third shells hold?