Composite Materials MCQ with answer and solution

Concept

The density of aluminium is about 2.7 g/cm³, which is about one-third of steel.

Formula

ρ_Al ≈ 2.7 g/cm³ = 2700 kg/m³

Step-by-step solution

1. The standard density of aluminium is 2.70 g/cm³. 2. This is the same as 2700 kg/m³. 3. So the answer is option B.

Explanation

Aluminium is a light metal. Its density is 2.7 g/cm³, which is about one-third of steel (7.85 g/cm³). So option B is correct.

Why the other options are wrong

A: 1.7 g/cm³ is close to magnesium. C and D: These values are too high for aluminium (titanium is about 4.5 g/cm³).

Shortcut

Aluminium = 2.7, steel = 7.85, about one-third.

Common mistake

Confusing aluminium with magnesium (1.74 g/cm³).