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Estimation of elements: Lassaigne, Kjeldahl, Carius

28 questions on Estimation of elements: Lassaigne, Kjeldahl, Carius from the Structural Identification and Practical Organic Chemistry chapter: 6 NEET level, 11 JEE Main, 11 JEE Advanced. Each one opens with its answer and solution.

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In the Lassaigne test for nitrogen, the Prussian blue colour is due to the formation of NEET level
A compound containing both nitrogen and sulphur is fused with a limited amount of sodium. The sodium extract is acidified and treated with FeCl3. A blood-red co... NEET level
The sodium extract of an organic compound gives a violet colour with a freshly prepared solution of sodium nitroprusside. The element present is NEET level
Kjeldahl's method cannot be used for the estimation of nitrogen in NEET level
In the Carius method, the sulphur of an organic compound is finally weighed as NEET level
A clean copper wire is dipped in an organic compound and held in the non-luminous Bunsen flame. A green or blue-green flame indicates the presence of NEET level
A compound containing C, N, S and Cl is fused with sodium. Before adding AgNO3 to the sodium extract for the chlorine test, the extract is acidified with dilute... JEE Main level
The sodium extract of an organic compound, acidified with dilute HNO3 and boiled, gives a yellow precipitate with AgNO3 that does not dissolve in conc. aqueous ... JEE Main level
Which of the following can be analysed correctly for nitrogen by the Kjeldahl method? JEE Main level
In a Liebig combustion, 0.215 g of an organic compound gave 0.102 g of H2O and 0.352 g of CO2. Using H = 1, C = 12, O = 16, the percentage of hydrogen in the co... JEE Main level
In a Carius estimation, 0.32 g of an organic compound gave 0.453 g of AgBr. With Ag = 108 and Br = 80, the percentage of bromine in the compound is JEE Main level
In a Dumas estimation, 0.315 g of an organic compound gave 47.2 mL of N2 measured at STP (molar volume 22400 mL). With N = 14, the percentage of nitrogen is JEE Main level
An organic compound contains only C, H, N and O. Analysis gave 61.0% C (Liebig), 5.1% H (Liebig) and 11.8% N (Dumas). The percentage of oxygen, obtained by diff... JEE Main level
Prussian blue, formed in the Lassaigne test for nitrogen, has the formula Fe4[Fe(CN)6]3. The total number of cyanide ligands in one formula unit is JEE Main level
The sodium extract of an organic compound (fused with excess sodium) gives a black precipitate with lead acetate in acetic acid, but gives neither Prussian blue... JEE Main level
Which of the following compounds cannot be analysed correctly for nitrogen by the Kjeldahl method? JEE Main level
4-Chloroaniline is fused with excess sodium metal and the sodium extract is prepared. Which species are present in the extract? JEE Main level
In a Carius estimation, 0.28 g of a sulphur-containing organic compound gave 0.466 g of BaSO4. Using Ba = 137, S = 32, O = 16, the percentage of sulphur is JEE Advanced level
In a Dumas estimation, 0.24 g of a compound gave 36.0 mL of moist nitrogen collected over water at 27 degC and a total pressure of 756 mm Hg. Aqueous tension at... JEE Advanced level
In the estimation of phosphorus, 0.35 g of an organic compound was heated with fuming HNO3, the phosphoric acid formed was precipitated as MgNH4PO4 and ignited ... JEE Advanced level
A compound containing only C, H and O (0.215 g) on Liebig combustion gave 0.473 g of CO2 and 0.1548 g of H2O. Oxygen is obtained by difference. Using H = 1, C =... JEE Advanced level
A compound containing C, N, S and Cl is fused with excess sodium (so no thiocyanate forms). The sodium extract is acidified with dilute HNO3 but is NOT boiled, ... JEE Advanced level
A dibromoalkane has the general formula C_nH_2nBr2. In a Carius estimation, 0.404 g of it gave 0.752 g of AgBr (Ag = 108, Br = 80, C = 12, H = 1). The molecular... JEE Advanced level
In a Liebig combustion train the tube of anhydrous CaCl2 (absorbs water) is normally placed before the tube of concentrated KOH solution (absorbs CO2, and also ... JEE Advanced level
Which statements about the Beilstein test are correct? JEE Advanced level
Benzenesulfonamide, C6H5SO2NH2, is fused with excess sodium (so that thiocyanate is not formed) and the sodium extract is tested. Which observations are correct... JEE Advanced level
Which statements about estimation of elements by the Carius method are correct? JEE Advanced level
In a Kjeldahl estimation, 0.750 g of an organic compound was digested and the ammonia evolved was absorbed in 40.0 mL of 0.250 M H2SO4. The excess acid required... JEE Advanced level