the first excited state of the nucleus of uranium-235 is 0.051 MeV above the ground state. what is the wavelength of the photon emitted when the nucleus makes a transition to the ground state? (in meters)

2 answers

Convert 0.051 MeV to energy in Joules.
1 eV = 1.6*10^-19 J
1 MeV = 1.6*10^-13 J

Call it E.

Then use
(wavelength) = E/(h c)

where h is Planck's constant and c is the speed of light.
drwls made one crucial error.

Wavelength equals (h c) / E, because who in their right mind would think that the wavelength is directly proportional to energy?