Need help with electron orbitals energies

Not really sure how to answer this...

Which orbital has the highest energy within Cobalt and which orbital has the lowest energy and explain.

What would you think the answer is based on writing out the electron configuration of Co?

1s2, 2s2, 2p6, 3s2, 3p6,4s2, 3d7

I'm confused, is 3d the highest energy and 1s2 the lowest, I don't get why

Which electron is the easiest to remove? That electron has the highest energy.

Yes, 1s2 is the lowest.

Okay so the electron 3d7 would be the easiest to remove so that would mean it would have the highest energy...? So having a higher or lower energy is due to how easy it is to remove an electron or how hard due to shieding etc?

Have you learned which electrons are lost first when transition metals form ions?

Have you learned which electrons are lost first when transition metals form ions?

no actually is it that you only put one electron in 4s, then fill 3d, then come back to 4s?

If you really want to understand this then read the following.

http://www.chemguide.co.uk/atoms/properties/3d4sproblem.html

If you really want to understand this then read the following.

http://www.chemguide.co.uk/atoms/properties/3d4sproblem.html

After reading everything am I right in thinking that 4s is the orbital with the highest energy as its the last energy level to be filled and the furthest from the nucleus containing the valence electrons.
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When talking about which orbital has the highest energy it hasn't got anything to do with shielding etc right? Just which energy level is filled first and how close it is to the nucleus?

The 4s is indeed the highest energy in Co. You will not need to explain this in A level questions. You only have to talk about shielding etc when comparing IE across a period or down a group.