Final answer:
To convert from molecules to moles for Tl, divide the number of molecules by Avogadro's number, so 1.00 × 1026 molecules equals 166 moles of Tl.
Step-by-step explanation:
To convert molecules to moles, you can use Avogadro's number, which is 6.02 × 1023 molecules per mole. For 1.00 × 1026 molecules of Tl, you divide the number of molecules by Avogadro's number to find the number of moles:
Number of moles = Number of molecules ÷ Avogadro's number
Number of moles = 1.00 × 1026 molecules Tl ÷ 6.02 × 1023 molecules/mol
Number of moles = 1.66 × 102 mol Tl
This calculation shows that there are 166 moles of Tl in 1.00 × 1026 molecules.