Sometimes, the colour observed in Lassaigne's test for nitrogen is green. It is because

Options

A. of green colour of ferrous sulphate
B. ferric ferrocyanide is also green
C. of green colour of copper sulphate
D. of excess of `Fe^(3+)` ions whose yellow colour makes the blue colour of ferric ferrocyanide apper green.

Answer

d

Explanation

Although blue coloured ferric ferrocyanide is formed but due to the presence of yellow coloured `Fe^(3+)` salts, the blue colour gives the shade of green.