How many moles of methane are in 7.31x10^25 molecules?

121.37 moles.

Explanation:

Always one mole of any molecule contains Avogadro number of molecules.

So one mole of methane contains 6.023*10^23 molecules.

Now we need number of moles of methane in 7.31*10^25 molecules.

This is just cross multiplication stuff.

6.023*10^23 molecules —————- 1 mole

7.31*10^25 molecules ——————- ?

= (7.31*10^25) / (6.023*10^23)

= 121.37 moles.