Final answer:
To find the number of moles of water in 8.1 x 10²⁵ water molecules, divide the number of molecules by Avogadro's number.
Step-by-step explanation:
To determine the number of moles of water in 8.1 x 1025 water molecules, we need to use Avogadro's number, which states that 1 mole of any substance contains 6.022 x 1023 particles (atoms or molecules). In this case, we have 8.1 x 1025 water molecules. To find the number of moles, we divide the number of molecules by Avogadro's number:
Number of moles of water = 8.1 x 1025 water molecules / (6.022 x 1023 molecules/mol) = 134.50680836931252 moles of water