1. A pale green substance X contains one cation and one anion. The following table shows the observations of tests on an aqueous solution of X.
Test
Procedure of test
Observation
I
Adding dilute nitric acid to a solution of X, followed by silver nitrate solution
A white precipitate forms.
II
Adding dilute sodium hydroxide solution to a solution of X
A green precipitate forms.
III
Adding a solution of X to a purple solution
The colour of the purple solution changes to pale yellow.
A) Explain the observation in test II.
B) i) suggest what the purple solution might be.
ii) write an ionic equation for the reaction occurred in test III.