TIPS

• Objects made of iron or steel can rust.
• Two factors that cause rusting are air and water.
• If any one of these two factors is absent, then rusting cannot take place.
• Rusting can be prevented by keeping objects made of iron or steel away from air and water. Example: applying grease or oil to the surface of an iron or steel object prevents air and water (moisture) from reaching the surface.

COMMON MISTAKES

The figure below shows an investigation.

What happens after a week?

1. The mass of the nail decreases
2. The nail turns reddish
3. The water changes colour
4. The nail has no change

The correct answer is B

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