How many electrons maximum can have n + l = 4 in an atom.

n + l = 4

where,

l = angular momentum quantum number

n = Principle quantum number

From Energy level of electrons

l ≤ n - 1

The values of n and l will be 3,1 and 4,0 respectively.

Case I:

n = 3, l = 1

so, this represents 3p subshell.

Hence, maximum no. of electrons = 6

Case II:

n = 4 ,l = 0

so, this represents 4s subshell.

Hence, maximum no. of electrons = 2.

Therefore, from case I and II:

Total no. of electrons = 6 + 2 = 8