Preventing rusting by galvanising

3 marks · Easy

The picture below shows a steel fence post that has rusted at the base after several years in a damp garden.

(a)

State two conditions necessary for rusting to occur on the steel post.

[2 marks]

(b)

Name one method, other than painting, which could have prevented rusting of the steel post.

[1 mark]

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

Show answer

(a) Presence of oxygen and water

(b) Oil/grease, plastic coating, or galvanising

Show mark scheme and worked solution

Marking points

B1 (a) · 1 mark · States 'oxygen' as necessary for rusting.

B2 (a) · 1 mark · States 'water' as necessary for rusting.

B3 (b) · 1 mark · Names a valid method other than painting (accept: oil/grease, plastic coating, galvanising/zinc coating).

Worked solution

a) The two necessary conditions for rusting of the steel post are the presence of oxygen and water.

b) One method that could have prevented rusting is coating the steel with zinc (galvanising), or covering it in oil/grease, or using a plastic coating.