I have no idea how to do this problem, and I've been searching through my book for an hour. Help please?

An energy of 2.0x10^2 kJ/mol is required to cause a cesium atom on a metal surface to lose an electron. Calculate the longest possible wavelength of light that can ionize a cesium atom. In what region of the electromagnetic spectrum is this radiation found?

3 answers

How many kilocalories are released by freezing 4.6 moles of H20?
You are not likely to obtain an answer by piggy backed questions; I suggest you post a new question at the top of the board.
E = hc/wavelength
Substitute h, c, and E and solve for wavelength. E is the energy/atom; to obtain that use 200,000 J/mole and convert to an atom by dividing by 6.022E23.
Is that visible light? Convert to Angstroms. 1 A = 1E-8 cm and 4000-7000 A is visible.