To convert the density from the CGS system ($g/cm^3$ or $g/cc$) to the MKS (SI) system ($kg/m^3$), we use the standard conversion factors for mass and length.

1. Conversion Factors: Mass: $1 \text{ g} = 10^{-3} \text{ kg}$. Volume: $1 \text{ cm} = 10^{-2} \text{ m}$, so $1 \text{ cm}^3 = (10^{-2} \text{ m})^3 = 10^{-6} \text{ m}^3$.

2. Derived Conversion for Density: $1 \frac{\text{g}}{\text{cm}^3} = \frac{10^{-3} \text{ kg}}{10^{-6} \text{ m}^3} = 10^3 \frac{\text{kg}}{\text{m}^3} = 1000 \frac{\text{kg}}{\text{m}^3}$ This direct conversion is listed in the NCERT Appendices .

3. Calculation: Given density $= 0.5 \text{ g/cc}$. $0.5 \times 1000 = 500 \text{ kg/m}^3$

Thus, the numerical value in MKS units is 500.