Metallic oxides of zinc, magnesium and copper were heated with the following metals.

Metal	Zinc	Magnesium	Copper
Zinc oxide	-	-	-
Magnesium oxide	-	-	-
Copper oxide	-	-	-

In which cases will you find displacement reactions taking place ?

You are given a hammer, a battery, a bulb, wires and a switch.

$(a)$ How could you use them to distinguish between samples of metals and non-metals ? 

$(b)$ Assess the usefulness of these tests in distinguishing between metals and non-metals.

Give reasons : Carbonate and sulphide ores are usually converted into oxides during the process of extraction.

You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.

Give an example of a metal which

$(i)$ is a liquid at room temperature.

$(ii)$ can be easily cut with a knife.

$(iii)$ is the best conductor of heat.

$(iv)$ is a poor conduct of heat.

Food cans are coated with tin and not with zinc because