A sample of gold at 358 K was added to 2.21 x 10⁸ ng of water. The initial water temperature was 298 K, and the final temperature at thermal equilibrium was 305 K. If the specific heat capacity of gold is 0.031 cal/(g ∙°C), how many gold atoms are in the sample of gold?
a. 30 ppm
b. 60 ppm
c. 300 ppm
d. 200 ppm