Illustrate and describe the sequence in which ten electrons occupy the five orbitals related to an atoms d sublevel

In an atom, subshell is defined as the set of states in a given shell that have the same azimuthal quantum number (ℓ).  

For a d-subshell, the value of azimuthal quantum number (ℓ) is 3. Also, a d-subshell contains 5 atomic orbitals, namely , that can be occupied by 2 electrons each.

The filling of electrons in a subshell, such as the d-subshell, of a given shell is governed by the Hund's Rule of maximum multiplicity.

According to this rule, firstly all the 5 atomic orbitals of the d-subshell are singly filled and then the electrons are paired.

Since, a d-subshell can contain 10 electrons.

Therefore, firstly the 5 atomic orbitals are occupied with one electron each

Then the remaining five electrons, results in the pairing of electrons in each d-atomic orbital.

As it can be seen from the molecular formula of wolframite that is FeWO₄, that there is one mole of iron that is Fe in 1 mole of wolframite ( FeWO₄).

1 mole of Fe= 1 × 6.023 × 10 ²³ atoms of Fe

So there are 6.023 × 10 ²³ atoms of Fe are there in 1 moles of wolframite, FeWO₄.

So number of atoms of iron is  6.023 × 10 ²³ in 1 moles of wolframite, FeWO₄.