There are two ways the coins could have been made to look gold.
Hypothesis 1: The suspects painted the silver-looking coins with gold paint. The gold paint would add matter to the silver-looking coins. The zinc metal could help the gold paint look real.
Hypothesis 2: The suspects heated the silver-looking coins. This mixes the zinc and copper metals. Mixing does not add matter. This mixture makes the coins look gold.
Use the mass data and the evidence to choose a hypothesis.
Explain your answer.
To choose between these two hypotheses, we need to consider the mass data and other evidence. If the suspects painted the coins with gold paint, then the mass of the coins would have increased due to the added matter of the paint. On the other hand, if the suspects heated the coins, the mass would not have changed as no new matter would have been added.
According to the evidence, the mass of the gold-looking coins is the same as the mass of the silver-looking coins. This suggests that hypothesis 1, that the suspects painted the coins with gold paint, is less likely to be true. If the coins were painted, we would expect their mass to have increased due to the addition of paint.
Therefore, hypothesis 2, that the suspects heated the coins to create a mixture of zinc and copper, which gave the coins a gold appearance, is more likely to be true. This process would not have added any new matter to the coins, which explains why their mass did not change.