Suggest the conditions needed for hydrogen and iodine to react. give reasons for your answer.

HI can be prepared by combing H2 and I2. This reaction is used to generate high-purity samples. This mixture of gases is being irradiated with the wavelength of light equal to the dissociation energy of I2, about 578 nm. This supports a mechanism whereby I2 first dissociates into 2 iodine atoms, which each attach themselves to a side of an H2 molecule and break the H−H bond.