What is the total number of molecules in 23 moles of oxygen?

To find the total number of molecules in 23 moles of oxygen, you can use Avogadro's number, which is (6.02 \times 10^{23}) molecules per mole. This number represents the quantity of molecules or atoms in one mole of a substance.

To calculate the total number of molecules in 23 moles of oxygen, you multiply the number of moles by Avogadro's number:

[

\text{Total molecules} = \text{number of moles} \times \text{Avogadro's number} = 23 \times 6.02 \times 10^{23}

]

Performing the multiplication gives:

[

23 \times 6.02 \times 10^{23} = 1.386 \times 10^{25}

]

When rounded appropriately, this results in (1.38 \times 10^{25}) molecules. Therefore, the total number of molecules in 23 moles of oxygen is correctly represented by this calculation, which corresponds to the first choice.