What is the energy in kj/mol of radiation with wavelength of
6.61m?

Explanation:

It is known that relation between frequency and wavelength is as follows.

                     f =

where,    c = speed of light

            = wavelength

Hence, first we will calculate the frequency as follows.

                f =

                  =

                  = s

Now, the relation between energy and frequency is as follows.

              E = hf

where,    h = planck's constant = J/s

             E =

                =

or,            =

As one mole contains atoms in a substance.

Hence, there are

                     = kJ/mol

Thus, we can conclude that radiation with wavelength of  6.61 m emits kJ/mol of energy.