What is the energy of a K x-ray photon in tantalum

[MrDMD83]

Homework Statement

The atomic number of tantalum is Z = 73. According to the Bohr model, what is the energy (in joules) of a K X-ray photon?

Homework Equations

Energy= -(13.6 eV)Z^2/n^2

The Attempt at a Solution

I don't know what to use for n

 

[JeffKoch]

What is the definition of a K x-ray transition? That should give you the answer.