Answer:
.757 moles of Gd is present in a sample containing 4.56x10^22 atoms of Gd.
Step-by-step explanation:
Atoms --> Moles
1. Take the given number and put it over 1
(4.56x10^22 atoms/1)
2. Multiply by 6.022x10^23 to go from atoms to moles
(4.56x10^22 atoms/1) (1mol Gd/6.022x10^22 atoms)= .757223513...
3. Round by sigfigs
4.56 has three sigfigs
=.757 mols