Mass of one Avogadro's number of O atom is equal to 16 g.

Explanation:
Avogadro's number is defined as the number of particles (atoms, molecules, ions, etc.) present in one mole of a substance. It is equal to 6.022 x 10^23 particles/mol.

The atomic mass of oxygen (O) is 16 amu (atomic mass unit). One amu is defined as 1/12th the mass of a carbon-12 atom.

To calculate the mass of one mole of oxygen atoms, we need to multiply the atomic mass of oxygen (16 amu) by Avogadro's number (6.022 x 10^23 atoms/mol). This gives us:

Mass of one mole of oxygen atoms = 16 amu x 6.022 x 10^23 atoms/mol
= 96.32 x 10^23 amu/mol

To convert this to grams, we need to use the conversion factor 1 amu = 1.66054 x 10^-24 g. This gives us:

Mass of one mole of oxygen atoms = 96.32 x 10^23 amu/mol x 1.66054 x 10^-24 g/amu
= 15.9994 g/mol

Rounding off to two decimal places, we get the mass of one oxygen atom as:

Mass of one oxygen atom = 15.9994 g/mol / 6.022 x 10^23 atoms/mol
= 2.657 x 10^-23 g/atom

To find the mass of one Avogadro's number of oxygen atoms, we simply multiply the mass of one oxygen atom by Avogadro's number. This gives us:

Mass of one Avogadro's number of oxygen atoms = 2.657 x 10^-23 g/atom x 6.022 x 10^23 atoms/mol
= 15.9994 g/mol
= 16 g

Therefore, the mass of one Avogadro's number of O atoms is equal to 16 g.