Principle Quantum number explains the main energy level, in other words it represent the main shell. It is represented by "n". Greater the value of n greater is the distance from nucleus.
Principle Quantum Number of Tellurium (Te):
Electronic Configuration of Te is as follow,
[Kr] 4d¹⁰, 5s², 5p⁴
It is shown in electronic configuration of Te that the valence electrons are present in 5th shell.
Result:
As valence electrons are present in 5th shell, so the Principle Quantum Number for the outermost electron of Te is 5.
n = 5