Th e energy required to break one mol of Cl-Cl bonds in Cl2 is 242 kJmol-1. The longest wavelength of light capable of breaking a single Cl-Cl bond is
A. 594nm
B.640nm
C. 700nm
D.494nm
Bond energy of single bond = 2426.023×1023=4.017×10−22KJ=4.017×10−19J
Now E=hcλ or λ=hcE
=6.626×10−34×3×1084.017×10−19=494nm