Question

What is the maximum number of electrons that can have n=4, mi= -1 in an atom?

Also, explain how you got that answer. I am confused.

Answer 1

N = 4 is set.
l may have values of 0, 1, 2, etc up to a maximum of n-1; therefore, l may be
0, 1, 2, or 3,

ml can have values of -l to +l in increments of 1 including 0.

If l = 0, ml must be 0.
If l = 1, ml can be -1, 0, +1; therefore, you can place 2 electrons there.
If l = 2, ml can be
-2, -1, 0, +1, +2; therefore, there can be two more electrons in this -1.
If l = 3, ml can be
-3, -2, -1, 0, +1, +2, +3; therefore, we can place two more electrons in this -1.
If I understand the problem correctly, we can place six (6) electrons in those three orbitals.

Answer 2

So, the maximum electrons is 6 right?

Answer 3

That's what I count. But you need to go through the reasoning and confirm that.