Final answer:
The number of uranium atoms in 8.9g of pure uranium is found by dividing the mass by molar mass to get the number of moles, then multiplying by Avogadro's number, resulting in 2.24×10²⁴ uranium atoms (option c).
Step-by-step explanation:
To determine how many uranium atoms are in 8.9g of pure uranium, we can use Avogadro's number and the molar mass of uranium. First, we need to find out the number of moles in 8.9 grams. The molar mass of uranium (assumed to be isotope U-238 here) is approximately 238.05 g/mol. So, the number of moles in 8.9 grams is:
Number of moles = mass / molar mass = 8.9 g / 238.05 g/mol
Once the moles are calculated, we multiply by Avogadro's number (6.02 × 10²³ atoms/mol) to find the number of atoms. Applying this:
Number of atoms = (8.9 g / 238.05 g/mol) × (6.02 × 10²³ atoms/mol)
After calculating the above expression, we find that option (c) 2.24×10²´ is the correct number of uranium atoms in 8.9g of pure uranium.