40. Solving a chemistry problem

7. Explain the following observations and write the reaction equations: when an alkali is added to a solution of a chromium (III) compound, a gray-blue precipitate is released, which is transferred to a green solution by the action of an excess of alkali. Adding bromine to it when heated changes the color of the solution to yellow. Adding acid to the resulting solution changes the yellow color to orange. After pouring hydrogen sulfide water into this solution, a yellow precipitate precipitates, and the solution becomes green.