Which characteristic is given by the principal quantum number?
a. orbital size
b. orbital mass
c. orbital shape
d. orbital orientation

Option a: orgital size

The bigger the principal quantum number the bigger the orbital (and the higher the energy).

Ortital mass is not related with quantum number.

Orbital shape (which may be s, p, d or f) is given by secondary quantum number (l).

And ml, magnetic quantum number, gives the orientation of the orbital in the space.

Answer( precipitate );