What is the maximum number of d orbitals in a principal energy level?

The answer is: 5 d-orbitals.

Principal quantum number (n) describes the size of the orbital.

There are one s orbital (angular quantum number l=0), three p orbitals (angular quantum number l=1 and magnetic quantum number ml = -1,0,+1) and five d orbitals (angular quantum number l=2 and magnetic quantum number ml = -2,-1,0,+1,+2).

d-orbitals are butterfly shaped.

2b2t

explanation:

2b2t

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8