Hello candidate,

Due to a limitation on the number of answering modes available on the platform, it's not possible for me to provide you with the detailed answer but I can surely help you with the required steps.

First, the energy= -13.6× (z/n)^2 electron Volt, where N1 equals to 5 and N2 equals to 2. Then, use the equation of Energy= hc/ width, in order to calculate the width of the box.

Hope it helps!!