Answer:
12 orbitals
Explanation:
The suborbital = d orbital.
n = 4
The orbital is 4d.
There are 5 degenerate orbitals of d orbitals. Thus m value, -2, -1, 0, +1, +2 .
Thus, number of orbitals = 5
The suborbital = f orbital.
n = 4
The orbital is 4f.
There are 7 degenerate orbitals of f orbitals. Thus m value, -3, -2, -1, 0, +1, +2, +3
Thus, number of orbitals = 7
Total number of orbitals = 7 + 5 = 12