1.1. A student performed the following tests to identify an unknown white salt X.

1. Silver nitrate solution was added to an aqueous solution of X which gave a yellow precipitate of compound A.

2. Concentrated ammonia solution was added and compound A did not dissolve.

3. Sodium carbonate solution was added to another aqueous solution of X which gave a white precipitate B.

4. The white precipitate B was filtered and dried and then reacted with sulfuric acid to give a colourless solution containing compound C and a colourless gas D.

State the formulas the compounds A, B, C, D and X.

1.2. Write an equation to represent the reaction of aqueous compound X with sodium carbonate solution.

1.3. Explain why different precipitates are produced when [Fe(H₂O)₆]²⁺ and [Fe(H₂O)₆]³⁺ ions react with aqueous sodium carbonate solution.

Include in your answer the colour of the precipitates formed in both reactions and the formula of the precipitate produced from the reaction of hexaaquairon (II) complex.

1.4. State what you would observe when an excess of dilute ammonia is added to separate aqueous solutions containing [Cu(H₂O)₆]²⁺ and [Ag(H₂O)₄]⁺.

i) In your answer state the initial colour of the solution and the final observation that you would make.

In each reaction, write an overall equation for the formation of the final product from the initial aqueous metal ion.

ii) State the bond angles in the complex formed when excess of dilute ammonia reacts with [Ag(H₂O)₄]⁺.