Q 01/05

What is iron called once its carbon content rises above steel's limit of about 2%?

A) Wrought iron

B) Sponge iron

C) Cast iron

D) Meteoric iron

Answer · why

C) Cast iron

Cast iron holds roughly 2 to 4% carbon, which lets it melt and pour easily into moulds but leaves it brittle, so it cracks where steel would bend.

Q 02/05

Adding at least 10.5% of which element makes steel stainless?

A) Chromium

B) Manganese

C) Nickel

D) Titanium

Answer · why

A) Chromium

Chromium reacts with air to form a thin oxide layer that seals the surface, and if the steel is scratched the layer regrows by itself.

Q 03/05

Galvanized steel is coated in a layer of which metal to resist corrosion?

A) Tin

B) Zinc

C) Aluminium

D) Copper

Answer · why

B) Zinc

Zinc protects steel twice over: it seals out moisture, and where the coating is scratched the zinc corrodes in place of the steel.

Q 04/05

Which country produced 54% of the world's steel in 2023?

A) Japan

B) United States

C) India

D) China

Answer · why

D) China

American production was once centred on Pittsburgh, Bethlehem and Cleveland.

Q 05/05

Roughly how much steel does the world make each year?

A) 20 million tonnes

B) 200 million tonnes

C) 2 billion tonnes

D) 20 billion tonnes

Answer · why

C) 2 billion tonnes

2 billion tonnes is close: output was about 1.9 billion in 2023, which works out at more than 200 kg for every person on Earth.