That is data that you have to collect tho it depends on the experiment assigned by your teacher...
pls follow me
Explanation:
The mass of one atom of calcium is the same as the molar mass of the calcium. Also, the atomic mass of calcium is 40.078 g/mol.
B.
I hope this will help a bit (Forgive me of its wrong pls)
If 1mole ------------- is ---------------- 6.02*10²³
than 0.25mole ----- is ---------------- x
x = [0.25mole*6.02*10²³]/1mole = <u>1,505*10²³</u>
Soluble means it can be dissolved
Insoluble means it can't be dissolved