Answer:
In 1 molecule of PCl₃ (phosphorus trichloride), there is 1 phosphorus atom. Therefore, to find the number of phosphorus atoms in 3 molecules of PCl₃, you'll simply multiply the number of phosphorus atoms in 1 molecule by the number of molecules given:
Number of phosphorus atoms in 3 molecules of PCl₃ = Number of phosphorus atoms in 1 molecule × Number of molecules
Number of phosphorus atoms in 3 molecules of PCl₃ = 1 phosphorus atom/molecule × 3 molecules = 3 phosphorus atoms
Therefore, there are 3 phosphorus atoms in 3 molecules of PCl₃.