The density will quadruple.

Here's why:

* Density Formula: Density (ρ) is calculated as mass (m) divided by volume (V): ρ = m/V

* Doubling Mass: If you double the mass (2m), the density will also double.

* Halving Volume: If you cut the volume in half (V/2), the density will double again.

Combined Effect: Since you're doubling the mass and halving the volume, you're effectively multiplying the density by 2 * 2 = 4.