Question

what is Avogadro Number how to calculate with oxygen

Answer 1

Avogadro's number is constant for all gases.

At STP.... any gas of volume 22.4 Lt or 22.4 dm^3 will have 6.023 × 10^23 molecules.
Be it oxygen or hydrogen ... every gas would have 6.023 × 10^23 mooecules in this state.

Answer 2

Avogadro constant is 6,023 x 10^23 (sometimes make it simple, it can be 6 x 10^23). Avogadro constant shows that for every elemnent, substance, etc.), there’s always about 6,023 x 10^23 atoms in 1 mol of that type of substance.

More easily, 1 mol = 6(,023) x 10^23 atoms.

So, there’s 12 x 10^23 atoms of Oxygen, hence there’s 2 moles of Oxygen.

There’s an equation : m (mass of substance) = n (substance’s mol) x M (substance’s molar mass)

Now, what we need here is to identify “m” (mass).

n = 2 (as calculating above), M of Oxygen is 16

So that, m = 2 x 16 = 32 (g)

Concluding, 12 x 10^23 atoms of Oxygen is heavy as 32 (g)