Given:

Mass of a penny, \(m = 2.49 g\)

Volume of a penny, \(V = 0.349 cm^3\)

Converting \(cm^3\) to \(m^3\):

$$(0.349 cm^3) (10^{-6} m^3/cm^3)=3.49 \times 10^{-7} m^3$$

Density of copper, \(\rho_{cu} = 8.96 g/cm^3\)

If the penny were made of pure copper, its density would be equal to that of copper:

$$\rho_{penny} = \frac{m}{V} = \frac{2.49 g}{3.49 \times 10^{-7} m^3}=7.10 \times 10^6 kg/m^3$$

Since the calculated density of the penny is lower than that of copper, the penny is not made of pure copper.