Certain sum glasses having small of `AgCl` incroporated the lenses, on expousure to light of appropriate wavelength turns to gray colour to reduce the glare following the reactions:
`AgCloverset(hv)(rarr) Ag("Gray")+Cl`
If the heat of reaction for the decomposition of `AgCl` is `248 kJ mol^(-1)`, what maximum wavelength is needed to induce the desired process?

Photochromic sunglasses, which darken when exposed to light, contain a small amount of colourless AgCl(s) embedded in the glass. When irradiated with light, metallic silver atoms are produced and the lass darkens. AgCl(s)toAg(s)+Cl Escape of chlorine atoms is prevented by the rigid structure of the glass and the reaction therefore, reverses as soon as the light is removed. if 310 kJ/mol of energy is required to make the reaction proceed, what wavelength of light is necessary.?