To find the mass of the gold coin, you can use the formula:
\[ \text{Mass} = \text{Density} \times \text{Volume} \]
Given that the density of the gold coin is \(20 , \text{grams per cubic centimeter}\) and the volume is \(2 , \text{cubic centimeters}\), you can substitute the values into the formula:
\[ \text{Mass} = 20 , \text{g/cm}^3 \times 2 , \text{cm}^3 \]
Calculating this gives:
\[ \text{Mass} = 40 , \text{grams} \]
Therefore, the mass of the gold coin is \(40\) grams.