Calculate the wavelength of light required to break the bond between two chlorine atoms in a chlorine molecule. The Cl-Cl bond energy is 243 kJ/mol. (h = 6.6 × 10⁻³⁴ Js; c = 3 × 10⁸ m/s, Avogadro's number = 6.023 × 10²³ mol⁻¹)

The energy required to break one Cl-Cl bond = Bond energy per mol / Avogadro's number = (243 × 10³ J/mol) / (6.023 × 10²³ mol⁻¹) = 4.035 × 10⁻¹⁹ J
Let the wavelength of the photon required to break one Cl-Cl bond be λ.
λ = hc/E = (6.6 × 10⁻³⁴ Js × 3 × 10⁸ m/s) / (4.035 × 10⁻¹⁹ J) = 4.91 × 10⁻⁷ m
So, the correct option is C