C3: Quiz 2 – Answers
1) 60%
2) 73%
3) 80%
4) 81%
5) 70%
6) 33%
We worked out the relative formula masses for some of the compounds in this quiz in the previous quiz. Therefore, feel free to use the relative formula masses that you worked out in the previous quiz rather than working them out again.
1) Work out the percentage by mass of magnesium in magnesium oxide.
Magnesium oxide is MgO.
Mg = 24, O = 16
2) Work out the percentage by mass of oxygen in carbon dioxide. Give your answer to the nearest integer.
Carbon dioxide is CO2
C = 12, O = 16
3) Work out the percentage by mass of carbon in C2H6.
C = 12, H = 1
4) Work out the percentage by mass of bromine in FeBr3. Give your answer to the nearest integer.
Fe = 56, Br = 80
5) Work out the percentage by mass of chlorine in H2SiCl2. Give your answer to the nearest integer.
Cl = 35.5, Si = 28, H = 1
6) Work out the percentage by mass of sulfur in H2SO4. Give your answer to the nearest integer.
H = 1, S = 32, O = 16