in the ground state electron configuration of Fe3+, how many unpaired electrons are present? I thought it was 1, but im getting a wrong answer.

Answer 1

Ground state of 26Fe.
1s2 2s2 2p6 3s2 3p6 3d6 4s2
So to make the 3+ ion, we remove the 2 outside electrons (the 4s2 electrons) + 1 more from the 3d orbital. Therefore, the ground state for the 3+ ion is
1s2 2s2 2p6 3s2 3p6 3d5
Hund's rule of maximum multiplicity says that these electrons will go into unfilled shells for the ground state. So how many d orbitals are available? There are 5 d orbitals and we place 5 electrons in them; therefore, there must be 5 unpaired electrons.

Answer 2

how can you fill a flask with pure oxygen without mixing it with air

Answer 3

how can you fill a flask with pure oxygen without mixingit with air