False.Energy does not involve motion
The answer is 2Eu + 3H2O —> Eu2O3+3H2.
Or in other words, change the first one to 3 and the second to 3 as well.
The density of the sample is:
Density = mass / volume
Density = 9.85 / 0.675
Density = 14.6 g/cm³
If the sample has 95% gold, and 5% silver, its density should be:
0.95 x 19.3 + 0.05 x 10.5
Theoretical density = 18.9 g/cm³
The difference in theoretical and actual densities is very large, making it likely that the jeweler was not telling the truth.