I dont understand the photostability!!!!!!!

Just read up on google. You will definetly find it there.

Melosima, you miss the whole point of this website. It's for students that need help and want to contact tutors. They would have checked it out on Google first, of course, but still dont understand the problem.

Do you know the answer?

yeah

Hi - this sort of specific content will typically be covered in textbooks for your course. However, assuming you still do not understand give me a shout if you want walking through the concept.

The photo stability of silver halides is to do with the fact that silver halides are weak interactions and therefore when light is added the energy in the light can cause the bond to break apart, therefore silver halides are photosensitive.

Is decomposition of silver halides a redox reaction? Yes, the decomposition of silver halides involves the transfer of electrons and therefore is a redox reaction. If you remember oxidation states you will know that Cl has an oxidation state of -1 and therefore Ag must have an oxidation state of +1. This is true because they are in an ionic bond. When 2AgCl degrades it becomes 2Ag and Cl2 (sorry i can't do subscripts on my computer) the oxidation states of both 2Ag and Cl2 are 0 and therefore it is a redox reaction because the oxidation states changed. I know that isn't the best way to describe it, if you have any more questions let me know, but I would recommend looking up redox reactions in your text book and figuring out the half reactions for the equation 2AgCl --> 2Ag to Cl2.