Answer: 0.00135
Step-by-step explanation:
The Avogadro's number is the number of particles (atoms, molecules, or ions) in one mole of a substance and is equal to 6.02 x 10^23. We can use this value to convert the number of molecules of CH4 into moles.
Number of molecules of CH4 = 8.11 x 10^20
Number of moles of CH4 = (8.11 x 10^20) / (6.02 x 10^23)
Number of moles of CH4 = 0.00135 moles of CH4 (rounded to five significant figures)
Therefore, there are approximately 0.00135 moles of CH4 in 8.11 x 10^20 molecules of CH4.