The orbital diagram shown here has some mistakes in it. Indicate which of the following rules and principles were not observed when this diagram was constructed. Select all that apply.

1. aufbau principle
2. Pauli exclusion principle
3. Hund's rule

This is an orbital diagram:
I don't have arrows so,
< means up
> means down

<< <> <> <> <
4s 3d

Hund's Rule means the two electrons, when paired, must be of opposite spin. The first two arrows don't have that, that is one problem. The spacing isn't what you intended, I think, so I don't know about the others. A second is 3d fills (in most cases) before 4s. Those two are all I see.

For 4s, the arrows are up

For 3d, there were five boxes. The first three boxes the arrows are up and down. The fourth box has an arrow going up. And the, fifth is empty.

So, is this orbital diagram has a problem in aufbau principle or Pauli exclusion principle as well? What do you think?

Sorry for the missing words I writing this again:

For 4s, the box has two arrows going up. For 3d, there were five boxes. The first three boxes had two arrows are up and down (correctly) in each box. The fourth box has an arrow going up. And the, fifth box is empty.

So, is this orbital diagram has a problem in aufbau principle or Pauli exclusion principle as well? What do you think?

OK. Now that you've described it a little better, this is how I would go.

The << in 4s can't be because of the Pauli Exclusion Principle (No two electrons can have the same 4 quantum numbers).
The 3d should fill before the 4s; that's the Aufbau Principle (electrons fill the lower energy levels before filling the higher energy levels.)
The 3d electrons have an empty orbital BUT some electrons in the 3d orbitals are already paired and that can't be (because Hund's rule of maximum multiplicity says that electrons don't pair until all of the orbitals have at least one electron in them.)
Note: I may not have stated the rules EXACTLY the way they are in your text or notes BUT your text may have chosen different words to say the same thing.

Overall, all three selection: Pauli Exclusion Principle, Aufbau Principle and Hund's rule are the problems?

(In my text, it is similar to what you stated.)

To determine which rules and principles were not observed in the given orbital diagram, we will need to understand the rules and principles mentioned.

1. Aufbau Principle: According to the Aufbau Principle, electrons fill the lowest energy orbitals first before moving to higher energy orbitals.

2. Pauli Exclusion Principle: The Pauli Exclusion Principle states that each orbital can accommodate a maximum of two electrons with opposite spins (up and down). These electrons must have different spin quantum numbers.

3. Hund's Rule: Hund's Rule states that when filling degenerate orbitals (orbitals with the same energy level), electrons will occupy empty orbitals before pairing up in the same orbital.

Now, let's examine the given orbital diagram:
<< <> <> <> <
4s 3d

From the diagram, we can see that the 4s orbital is filled before the 3d orbital. This follows the aufbau principle since the 4s orbital has a lower energy level than the 3d orbital.

In terms of the Pauli Exclusion Principle, we can see that there are no more than two electrons in each orbital, and they have opposite spins (one up and one down). This means the Pauli Exclusion Principle is observed.

Hund's Rule states that when filling degenerate orbitals, the electrons will occupy empty orbitals before pairing up. In the given diagram, the 3d orbitals are not completely filled before pairing up. This violates Hund's Rule.

Therefore, the principle that was not observed in the given orbital diagram is Hund's Rule (3).