Doubt from atomic structure

#1


For
N=1 -> l=1 -> m= -1,0,1
N=2 -> l=0,2 -> m= 0 ; -2,-1,0,1,2
N=3 -> l=1,3 -> m= -1,0,1 ; -3,-2,-1,0,1,2,3
N=4 -> l=0,2,4 -> m= 0 ; -2,-1,0,1,2 ; -4,-3,-2,-1,0,1,2,3,4
For each M there are 2 electrons
6,12,20,30
I'm getting (3) instead of (4). Where am I going wrong?

#2

Its upto n=0, so count that too.

#3

I'm sorry I don't understand could you elaborate?

#4

Here 0 is also there so it might happen that n=0,2,4,6,... Are odds and n=1,3,5,7.. are even , try with that i will try on paper asap

#5

No, the approach is not wrong however the question asks for Electron number of n=1,2,3,4 and not number of electrons in each n=1,2,3,4.
Thus, the question needs to be approached this way