To calculate the number of molecules in 2.10 moles of carbon dioxide (CO2), we can use Avogadro's number, which is the number of entities (atoms, molecules, ions, etc.) present in one mole of a substance. Avogadro's number is approximately 6.022 x 10^23.

Using Avogadro's number, we can convert moles to molecules as follows:

Number of molecules = Number of moles × Avogadro's number

Substituting the given number of moles (2.10 moles) into the formula, we get:

Number of molecules = 2.10 moles × 6.022 x 10^23 molecules/mole

Number of molecules ≈ 1.265 x 10^24 molecules

Therefore, there are approximately 1.265 x 10^24 molecules in 2.10 moles of carbon dioxide.