Calculations quiz

1. Which particle(s) in an atom has a positive charge?

2. 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

3. To determine the formula of a metal oxide by combustion, magnesium is heated in a crucible. Why is a lid used?

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

5. Calculate the relative formula mass(Mr) of calcium hydroxide (Ca(OH)₂)

6. How many electrons can the third shell hold?

7. In terms of mass and atomic number, what are isotopes?

8. What is meant by the term molecular formula?

9. 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.