An organic compound whose empirical and molecular formula are same, contains 20% carbon, 6.7% hydrogen, 46.7% nitrogen and the rest oxygen. On heating it yields ammonia, leaving a solid residue. The solid residue gives a violet colour with dilute solution of alkaline copper sulphate. The organic compound is
(a) NH2COONH4
(b) HCOONH4
(c) NH2NHCHO
(d) NH2CONH2
Correct answer: (d) NH2CONH2
Explanation:
Empirical formula = Molecular formula
= CH2N2O Or NH2CONH2
H2NCONH2 + H2NCONH2 \(\overset {\Delta}\rightarrow\) H2NCONHCONH2 + NH3
When an aqueous solution of biuret is treated with dilute sodium hydroxide and a drop of copper sulphate, a violet colour is produced. This test is known as biuret test, and is characteristic of compounds having the group –CONH–