Question

Electron Shells,
How many atomic orbitals are there in universe?

Answer 1

How many atomic orbitals are there in a d subshell?

d subshell :
l = 2
m = -2, -1, 0, 1, 2

=> 5 orbitals

Answer 2

What is the maximum value of the secondary quantum number (l) allowed for atomic electrons with a principal quantum number n = 1?

n=1 => l = 0

Answer 3

In an atom, what is the maximum number of electrons that can have a principal quantum number n = 3?

n=3 :
l = 2,1,0

In n=1
l=2 has m=-2, -1, 0, 1, 2 => 5 orbitals
l=1 has m=-1, 0 , 1 => 3 orbitals
l=0 has m=0 => 1 orbital

total 9 orbitals => 9x2 = 18 electrons