D sublevel because the s sublevel has one orbital, the p sublevel has three orbitals, the d sublevel has five orbitals, and the f sublevel has seven orbitals. In the first period, only the 1s sublevel is being filled.
Explanation:
Fe. O
72.40/ 56 27.60/16
____________________
1.29/1.29 1.725/1.29
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1. :. 1
<h3>Emperical formula = FeO</h3>
1 mole ----------- 6.02x10²³ molecules
? moles --------- 1.9x10²⁵ molecules
moles = 1.9 x 10²⁵ * 1 / 6.02x10²³
= 1.9 x 10²⁵ / 6.02x10²³
= 31.561 moles
hope this helps!