Answer: option A. 2
Explanation: in the formula Sr3(PO4)2, the 2 behind (PO4) is affecting both P and O4. It means that we have P2 in the formula
Pure substances are substances which are homogenous in nature. They either consists of atoms of 1 kind or molecules of 1 kind. Atoms are seen in elements, where as molecules are seen in compounds like Acids, Bases, etc.
They mostly have fixed properties like boiling and melting points and are uniform in nature. :D
I think the answer might be 51.14% since the formula had to equal a 100% just add 41.86 and 6.98 and subtract the sum to 100.