In radioactive decay, is converted to with the emission of x-ray photon. what is the nature of decay?

The complete question is that,

" In radioactive decay 81 Rb is converted to 81 Kr with the emission of x-ray photon what is the nature of decay?"

Therefore, in order for Rb to Kr involves the conversion of a neutron to a proton, as the atomic mass remains constant but the proton number increases by one. This type of decay is referred to as beta decay.