1. Find the molar mass of P4S10

* Molar mass of P (phosphorus) = 30.97 g/mol

* Molar mass of S (sulfur) = 32.07 g/mol

* Molar mass of P4S10 = (4 * 30.97 g/mol) + (10 * 32.07 g/mol) = 444.56 g/mol

2. Calculate the moles of P4S10

* Moles = mass / molar mass

* Moles of P4S10 = 100 g / 444.56 g/mol = 0.225 moles

3. Determine the moles of phosphorus atoms

* Each mole of P4S10 contains 4 moles of phosphorus atoms.

* Moles of phosphorus atoms = 0.225 moles P4S10 * (4 moles P / 1 mole P4S10) = 0.90 moles P

Therefore, there are 0.90 moles of phosphorus atoms in 100 grams of P4S10.