Oxygen is a diatomic gas. How many oxygen molecules are in 16 grams of oxygen?
A) 0.5 molecules
B) 1.20 x 1024 molecules
C) 3.01 x 1023 molecules
D) 6.02 x 1023 molecules

                      3.011 × 10²³ O₂ Molecules

Explanation:

Data Given:

                Mass of O₂  =  16.0 g

                M.Mass of O₂  =  32.0 g.mol⁻¹

Step 1: Calculate Moles of O₂ as,

                Moles  =  Mass ÷ M.Mass

Putting values,

                Moles  =  16.0g ÷ 32.0 g.mol⁻¹

                Moles  =  0.50 mol of O₂

Step 2: Calculate number of Carbon atoms,

As 1 mole of any substance contains 6.022 × 10²³ particles (Avogadro's Number) then the relation for Moles and Number of Oxygen Molecules can be written as,

      Moles  =  Number of O₂ Molecules ÷ 6.022 × 10²³ Molecules.mol⁻¹

Solving for Number of C atoms,

      Number of O₂ Molecules  =  Moles × 6.022 × 10²³ Molecules.mol⁻¹

Putting value of moles,

      Number of O₂ Molecules  =  0.50 mol × 6.022 × 10²³ Molecules.mol⁻¹

      Number of O₂ Molecules  =  3.011 × 10²³ O₂ Molecules