1) When 1.17g of potassium is heated in oxygen 2.13g of an oxide are produced. In the case of this oxide the empirical and molecular formulae are the same. What is the molecular formula of the oxide produced?

2)A solution of copper sulphate reacts with sodium hydroxide solution to produce a precipitate of copper hydroxide according to the following equation

CuSO^4(aq) + 2NaOH(aq) -> Cu(OH)^2(s) + Na^2SO^4

What mass of sodium hydroxide would be needed to convert 15.95g of copper sulphate to copper hydroxide and what mass of copper hydroxide would be produced?

3) When 13.9g of FeSo^4.xH20 are heated 4g of solid iron(III) oxide are produced together with the loss of 1.6g of sulphur dioxide and 2.0g of Sulphur Trioxide. The rest of the mass loss being due to the warer of crystallization being lost. Use the data to write the full equation for the action of heat.

4) When an oxide of carbon containing 57.1% oxygen is burnt in the air the percentage of oxygen joined to the carbon increases to 72.7%. Show that this data is consistent with the combustion of carbon monoxide to carbon dioxide.