Which of the following is a common metal alloy?

• A. Iron
• B. Copper
• C. Steel
• D. Brass

Answer: (D)

Alloys are materials made by combining two or more elements to achieve properties that aren’t present in the elements alone. Brass is a classic example: it’s formed by mixing copper with zinc. This changes the material’s properties, giving it good malleability, a distinctive yellowish colour, and useful strength for things like fittings and musical instruments. The other options are pure metals in their elemental form—iron and copper. Steel is also an alloy (iron with carbon and other elements), but brass is the familiar, straightforward two-element alloy most people recognize, which is why it’s chosen here.