Suppose an unknown substance has a melting temperature of 1,200 degrees Celsius and a density of 16.7 g/cm3. However, the different individual atoms that make up the element have very different melting temperatures and densities. Which is the unknown substance most likely

Answer 1

Is this a multiple choice question?
What are then choices?
With a density that high, one alloy constituent is likely to be gold. The other would have to have a higher melting point than gold, and could be palladium, for example.

Gold "crown" alloys that are use to repair teeth have properties similar to those you mentioned.