For the first one I think you need to: 1. Calculate the volume of the cube in cubic centimetres. 2. Calculate the total density of the cube And then I get a but lost as well. The thing for the second problem is that you're not using enough significant numbers. You're right about the numbers, but you need to use more of them behind the comma, if that makes sense?
Hmm, some common mistake points for the first one: When you're converting a volume in cubic inches to cubic cm, don't forget that you have to apply the inches-to-cm conversion factor 3 times, once for each dimension. The cube is calcium carbonate, but the problem specified the number of oxygen atoms. How many oxygen atoms are in a calcium carbonate molecule?
