In the modern wave-mechanical model of the atom, the orbitals are regions of the most probable location of

The orbital is the probable location of the electron of an atom.

Always remember the difference between Bohr and wave-mechanical model in terms of electrons!  

Your questions answer is Electron!  

But you should also know Bohr said electrons are in orbitals in a fixed proportion, but modern wave mechanical disagrees with this and said electrons are arranged in a very complex random proportion in a region called orbital!  

Hope this helped

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he would use the colour black

i don,t know so just answer mine