Final answer:
To find how many moles of PCl₃ contain 3.68x10²⁵ chlorine atoms, divide the total number of chlorine atoms by three and then use Avogadro's number to convert molecules to moles, resulting in 20.4 moles PCl₃.
Step-by-step explanation:
The question asks how many moles of PCl₃ contain 3.68x10²⁵ chlorine atoms.
Firstly, we need to recognize that each molecule of PCl₃ contains three chlorine atoms. To find the number of moles of PCl₃, we can divide the total number of chlorine atoms provided by three to find the number of PCl₃ molecules.
Step 1: Calculate the number of PCl₃ molecules: (3.68x10²⁵ Cl atoms) / (3 Cl atoms/PCl₃ molecule) = 1.2267x10²⁵ PCl₃ molecules.
Step 2: Convert PCl₃ molecules to moles using Avogadro's number: (1.2267x10²⁵ PCl₃ molecules) / (6.022x10² molecules/mol) = 20.4 moles PCl₃.
Therefore, the correct answer is B. 20.4 moles PCl₃.