If the heat of combustion of hydrogen is -285.8kJ,
What is the heat of formation of water?

5SO\(_2\)(g) + 2KMnO\(_4\)(aq) + 2H\(_2\)O(l) → K\(_2\)SO\(_4\) + 2MnSO\(_4\)(aq) + 2H\(_2\)SO\(_4\)(aq)
In the reaction above, the products give a

An element used in the production of matches is

When calcium oxide is heated with carbon, the oxide will

A solution which on treatment with hydrochloric acid produces a colourless, odourless gas which turns lime water milky is most likely to be a