# What is the right quantum numbers of Copper?

Copper have $[Ar] 3d^{10} 4s^1$ electron configuration. And Zinc have $[Ar] 3d^{10} 4s^2$ electron configuration.

My question is, what is the right quantum numbers of last electron of copper? Is it $$a. n=3,l=2,m=+1,s=-1/2$$ or $$b. n=3,l=2,m=+2,s=-1/2$$

If I use A, the electron configuration of copper is $[Ar] 3d^{9} 4s^2$ and it isn't stable. But if I use B quantum numbers, it is the same with the last electron of zinc.

The correct quantum numbers for last electron of Copper ($\ce{Cu}$) would be $B. n=3,l=2,m=+2,s=-1/2$.