This is false, because copper is an element.
To be solution, it has to have at least 2 different substances. Solid solution of metals is often called alloy.
I think that the answer is 0.49
This disorder is inherited through DNA because there is a lack of pigmentation in the skin.
Fossil C is the youngest. Layers further down were placed earlier than others. Because C is on the top layer, it must be the youngest (unless a disaster mixed up all the layers!).