A student tests an unknown solid, solid X, and records the results in the table below. Test 1: a flame test on solid X gives a blue-green flame. Test 2: solid X is dissolved in water and aqueous sodium hydroxide is added dropwise and then in excess, giving a light blue precipitate that is insoluble in excess. Test 3: to a fresh portion of the solution, dilute nitric acid is added followed by aqueous barium nitrate, giving a white precipitate.