The total number of atomic orbitals in fourth energy level of an atom is:

The total number of atomic orbitals in a shell with principal quantum number $n$ is given by the formula:
$$\text{Number of orbitals}=n^2$$
For the fourth energy level ($n=4$):
$$\text{Number of orbitals}=4^2=16$$
These include one $4s$, three $4p$, five $4d$, and seven $4f$ orbitals ($1+3+5+7=16$).