A gas containing hydrogen like atoms with atomic number Z, emit photons in transition `n+2ton,` where `n=Z` and work function of metal is `4.2eV`. The photons are incident on the metal emitting electrons of minimum de Broglie wavelength `5A^(0)`

Options

A. the maximum `K.E` of photonelectron is `6eV`
B. the maximum `K.E` of photonelectron is `5 eV`
C. the value of Z is
D. the value of Z is `3`

Answer

A, C

Explanation

`13.6z^(2)[1/n^(2)1/(n+2)^(2)]=W+KE_(max)` and `KE_(max)=h^(2)/(2mlambda^(2)`