A student mixed three sodium salts accidentally. To identify these salts some tests were performed and it was found that 

(i) when the chromyl chloride test was performed a mixture of coloured gases was released and the NaOH solution turned yellow and gave a positive test, 

(ii) the brown ring test was positive but the brown coloured gas was not intensified on adding copper turnings on heating the mixture with concentrated $$\text{H}_2\text{SO}_4$$, 

(iii) an aqueous solution of the mixture was treated with $$\text{CHCl}_3$$ and chlorine water, and from this chloroform layer the layer test was performed, when a violet organic layer was first visible and then on more addition of concentrated $$\text{HNO}_3$$ it changed to orange yellow. The observations indicate the presence of