The number of oxygen molecules present in 16.0g of the gas is ______?
[Avogadro's number = 6.02 x 10^{23}]

Answer Details

The molar mass of oxygen gas (O_{2}) is 32 g/mol. Therefore, 16.0 g of oxygen gas will contain one-half the number of moles as its mass in grams. Number of moles = mass ÷ molar mass Number of moles of O_{2} in 16.0 g = 16.0 g ÷ 32 g/mol = 0.5 mol Since one mole of any substance contains Avogadro's number of particles (atoms or molecules), the number of oxygen molecules in 0.5 mol of O_{2} is: Number of molecules = Avogadro's number x Number of moles Number of molecules = 6.02 x 10^{23} x 0.5 = 3.01 x 10^{23} Therefore, the correct option is: 3.01 x 10^{23}.