Multiple choice The addition of NH4CNS to a neutral solution of cobalt(II) salt produces red precipitates yellow precipitates blue precipitates green precipitates Reveal answer Fill a bubble to check yourself C Correct answer Explanation Add 5 ml of dil. HCl to salt and boil it. Add 1 ml of amyl alcohol ether and 1 ml of NH4CNS solution. Shake well and the upper layer is coloured intense blue.