When an aqueous sample of X is warmed with aqueous sodium hydroxide and small pieces of aluminium, a gas is evolved that turns damp red litmus paper blue. If aqueous sodium hydroxide is then added to a different aqueous sample of X, a pale green precipitate is seen. What is X?
- Aammonium nitrate
- Bchromium(II) chloride
- Ciron(II) nitrate
- Diron(II) sulfate