metal + oxygen ---- metal oxide.

metal + water --- metal hydroxide + hydrogen.

The gas that reacts with metals mostly is oxygen.

When Metals react with the gas which is given off is called hydrogen.

metal + sulphuric acid --- metal sulphate + hydrogen.

Aluminium does not need to be painted because it forms a natural protective layer.

When a copper coin goes black and dull oxidation and tarnishing take place.

Gold does not react with the air.

To break bonds electricity is used.

Attaching a copper rod to iron would not reduce the corrosion rate.

When iron corrodes it reacts with chemicals in the environment to form compounds.