Calculate the number of molecules (N) of the substance in a given mass: (BaSO4) = 115g; (AgNo3) = 12g

Find the molar mass of barium sulfate.
M BaSO4 = 137 + 32 + 16 x 4 = 233 grams / mol;
The amount of substance will be:
M BaSO4 = 115/233 = 0.4936 mol;
One mole contains 6.022 x 10 ^ 23 molecules.
The number of barium sulfate molecules will be:
K BaSO4 = 0.4936 x 6.022 x 10 ^ 23 = 2.9725 x 10 ^ 23 molecules;
Let’s find the molar mass of silver nitrate.
M AgNO3 = 64 + 14 + 16 x 3 = 126 grams / mol;
The amount of substance will be:
M AgNO3 = 12/126 = 0.095 mol;
One mole contains 6.022 x 10 ^ 23 molecules.
The number of silver nitrate molecules will be:
K AgNO3 = 0.095 x 6.022 x 10 ^ 23 = 5.72 x 10 ^ 22 molecules;