Sagot :
i'll show you one of these, and then you can try the others. This is simple stoichiometry. You have 98 g CuSO4. In order to get to the number of molecules you ultimately need to multiply the number of moles you have by Avogadro's number (6.022x10^23), the number of particles in 1 mole of a substance. But first you need to find how many moles of CuSO4 you have. Step 1) find the molar mass of CuSO4 by adding up the atomic masses of each atom. You get 159.625. Step 2) Divide the mass that you are given by the molar mass. 98g/159.625=0.614mols. Step 3) Multiply the number of moles you calculated by Avogadro's Number. 0.614x(6.022x10^23)=3.697x10^23. That is your answer. Hope this helps! The other 2 problems are exactly the same, just follow the steps. Good luck!