Let's use the formula about density.
![\rho=(m)/(V)](https://img.qammunity.org/2023/formulas/chemistry/high-school/9kur6nx1zv5yn6pmaen9vo51nz3vc8vp9y.png)
Let's use the given magnitudes. The density is 10.5 g/mL but we need to approximate it to the whole number, and the volume is 6.0 mL.
![11((g)/(mL))=(m)/(6.0mL)](https://img.qammunity.org/2023/formulas/mathematics/high-school/kqdybz0yrbe05w341jmd61t9bxa4ytns28.png)
We have to multiply each side by 6.0 to find the mass.
![\begin{gathered} 11((g)/(mL))\cdot6=(m)/(6.0mL)\cdot6 \\ m=66g \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/1pevv9cgw2biuns2rv4p7mfts56z9zt8gc.png)
Therefore, the mass is 66 grams.