Steels, Rusting and preventions

Four test-tubes were set up as shown.

Each piece of iron was protected on one side by a different coating.

In which test-tube is the iron least likely to rust?

• A

• B

• C

• D

The steel bodies of cars can be protected from rusting by spraying them with zinc.

Why is zinc used?

• Zinc does not react with acidic exhaust fumes.

• Zinc forms a stable compound with iron.

• Zinc has a high melting point.

• Zinc is higher in the reactivity series than iron.

Four experiments on rusting are shown.

Which two experiments can be used to show that air is needed for iron to rust?

• 1 and 3

• 1 and 4

• 2 and 3

• 2 and 4

Iron pipes corrode rapidly when exposed to sea water.

Which metal, when attached to the iron, would not offer protection against corrosion?

• aluminium

• copper

• magnesium

• zinc

Which metal is used in the sacrificial protection of iron pipes?

• copper

• lead

• magnesium

• sodium

The diagram shows a boat made from iron.

Some magnesium blocks are attached to the iron below the water line.

Why does the magnesium stop the iron from rusting?

• Magnesium reacts in preference to the iron.

• Magnesium reacts to form a protective coating of magnesium oxide on the iron.

• The magnesium forms an alloy with the iron.

• The magnesium stops oxygen in the water from getting to the iron.

In which test-tube is the iron nail most likely to rust?

• A

• B

• C

• D

Experiments are set up to investigate the sacrificial protection of iron.

In which test-tubes will the iron rust?

• X only

• Y only

• X and Z only

• Y and Z only

Two pieces of iron, one with zinc attached and the other with copper attached, are placed separately in water as shown.

Which statements are correct?

1          The iron in Y will not rust.

2          The water in Z will turn blue.

3          The zinc in Y will be oxidised.

• 1, 2 and 3

• 1 and 2 only

• 1 and 3 only

• 2 and 3 only

Which element, if attached to iron immersed in salt water, would prevent the iron from corroding?

• carbon

• copper

• magnesium

• sulfur

• C