Which one is a chemical change: Rusting of iron or melting of iron?

Give differences between the displacement and double displacement reactions.

When a green iron salt is heated strongly, its colour finally changes to black and the odour of burning sulphur is given out.
$(a)$ Name the iron salt.
$(b)$ Name the type of reaction that takes place during the heating of iron salt.

Why is a combustion reaction considered an oxidation reaction?

$2 \, g$ of ferrous sulphate crystals are heated in a boiling tube.
$(i)$ State the colour of ferrous sulphate crystals both before heating and after heating.
$(ii)$ Name the gases produced during heating.
$(iii)$ Write the chemical equation for the reaction.

Translate the following statements into chemical equations and then balance them.
$(a)$ Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.
$(b)$ Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.