1. **State the problem:** We have a soil sample with a wet mass of 1000 g, volume of 640 cc, and moisture content of 200 g. Particle density is 2.63 g/cc. We need to calculate bulk density and soil porosity. 2. **Formulas:** - Bulk density $\rho_b = \frac{\text{dry mass}}{\text{total volume}}$ - Porosity $n = 1 - \frac{\rho_b}{\rho_p}$ where $\rho_p$ is particle density. 3. **Calculate dry mass:** $$\text{dry mass} = \text{wet mass} - \text{moisture} = 1000 - 200 = 800\text{ g}$$ 4. **Calculate bulk density:** $$\rho_b = \frac{800}{640} = 1.25\text{ g/cc}$$ 5. **Calculate porosity:** $$n = 1 - \frac{1.25}{2.63} = 1 - 0.475 = 0.525$$ 6. **Interpretation:** Bulk density is 1.25 g/cc, and soil porosity is 0.525 (or 52.5%).