To determine the quantity of Oxygen that contains the same number of molecules as 36 grams of water, we can use Avogadro's number (Nₐ), which represents the number of atoms, molecules, or ions present in one mole of a substance.

1. Calculate the number of molecules in 36 grams of water (H₂O):

First, we need to determine the number of moles of water in 36 grams. The molar mass of water (H₂O) is 18 grams per mole (2 x 1 gram for hydrogen + 16 grams for oxygen).

Number of moles of water (n) = mass (m) / molar mass (M)

n = 36 grams / 18 grams/mol

n = 2 moles of water

2. Use Avogadro's number to determine the number of molecules:

Avogadro's number (Nₐ) is 6.022 x 10^23 molecules per mole.

Number of molecules in 2 moles of water = 2 moles x 6.022 x 10^23 molecules/mole

Number of molecules in 2 moles of water = 1.2044 x 10^24 molecules

3. Determine the mass of Oxygen with the same number of molecules:

Since we want the same number of molecules in Oxygen (O₂), we can use the molar mass of Oxygen to calculate the corresponding mass. The molar mass of Oxygen (O₂) is 32 grams per mole (2 x 16 grams for oxygen).

Mass of Oxygen (m) = number of molecules (n) / Avogadro's number (Nₐ) x molar mass (M)

Mass of Oxygen = (1.2044 x 10^24 molecules) / (6.022 x 10^23 molecules/mole) x (32 grams/mole)

Mass of Oxygen ≈ 6.4 grams

Therefore, 6.4 grams of Oxygen contains the same number of molecules as 36 grams of water.