A rectangular metal bar has length $7.0,$cm, breadth $3.5,$cm, height $2.5,$cm and mass $140$ g. Calculate its density in $g/c{m}^3$ and determine if this density is close to that of pure aluminium ($2.70,g/c{m}^3$).

Step-by-step solution

1. Calculate the volume of the block: $V=7.0\times 3.5\times 2.5=61.25;c{m}^3$.
2. Compute density: $\rho =\frac{mass}{volume}=\frac{140}{61.25}\approx 2.29;g/c{m}^3$.
3. Compare with aluminium: $2.29$ is about $15$ lower than $2.70$, so it is not close.

Concept tested: Density of a metal

Published 16 October 2026 · How this solution was prepared and checked