1. The problem statement, all variables and given/known data Calculate the bond length for the NaCl molecule given that three successive wavelengths for rotational transitions are 23.1 mm, 11.6, mm and 7.71 mm. 2. Relevant equations I = h*wavelength/4pi*speed of light. 3. The attempt at a solution I don't understand how to incorporate the wavelengths. But the thing is, I have three wavelengths, not one. Should I take the difference between the three?