State two ways to prevent the rusting of iron.

An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be

Food cans are coated with tin and not with zinc because

Give reasons :  Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.

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.