Lassaigne's extract of thiourea, `SC(NH_(2))_(2)` is boiled with ferrous sulphate and then acidified with `HCl`, the colour of the resulting solution will be

When Lassaigne's extract (Na_(2)S) is acidified with acetic acid and then lead acetate solution is added to it, the colour of the precipitate is

When lassaigne's extract (Na_(2)S) is acidified with acetic acid and then lead acetate solution is added to it, the colour of the precipitate is

During Lassaigne's test for nitrogen, the sodium fusion extract i9s heated to boiling with ferrous sulphate crystals and then acidified with dilute sulphuric acid. If N is present, Prussian blue appears due to the formation of

The colour of the solution obtained when sodium fusion extract of urea is boiled with ferrous sulphate followed by acidification with concentrated sulphuric acid will be

The colour of the solution obtained when sodium fusion extract of urea is boiled with ferrous sulphate followed by acidification with concentrated sulphuric acid will be

When a copper plate is dipped into a solution of ferrous sulphate , the colour of the solution will change to

The Lassaigne's solution when heated with ferrous sulphate and acidified with sulphuric acid gave intense blue colour indicating the presence of nitrogen. The blue colour is due to formation of: