Question

why is silver chloride soluble in aqueous solution of methylamine?

Answer 1

Actually, it doesn't mean that if you have same metal ion with different halogens they must behave likewise. Halogens have different properties from up to down. One of the main reasons is that iodide ions have bigger radius in comparison to chloride ions and because of soft-soft and hard-hard rule like polar-polar and nonpolar-nonpolar, Iodine can't dissolve in NH3. Ammonia is hard compound because it is little in size but iodine is soft because of raidus. As a result soft can't dissolve in hard.