Chapter 9

In Lassaigne's test, the organic compound is first fused with sodium metal. The sodium metal is used because (a) The melting point of sodium metal is low. (b) Sodium metal reacts with elements present in organic compounds to form inorganic compounds. (c) All sodium salts are soluble in water. (d) All sodium salts are not soluble in water.

Sodium nitroprusside \(\mathrm{Na}_{2}\left[\mathrm{Fe}(\mathrm{CN})_{5} \mathrm{NO}\right]\) is used as reagent for detection of ____ and the compound formed is _____. (a) Sulphur, \(\mathrm{Na}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{5} \mathrm{NOS}\right]\) (b) Nitrogen, \(\mathrm{Na}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]\) (c) Sulphur, \(\mathrm{Na}_{2}\left[\mathrm{Fe}(\mathrm{CN})_{4} \mathrm{NOS}\right]\) (d) Sulphur, \(\mathrm{Na}_{2}\left[\mathrm{Fe}(\mathrm{CN})_{3} \mathrm{NOS}\right]\)

Molecular weight of acids can be detemined by (a) Silver salt method (b) Volumetric method (c) Plants chloride method (d) Victor Meyer's method

The prussian blue colouration obtained in the test for nitrogen in the organic compound is (a) \(\mathrm{K}_{4}[\mathrm{Fe}(\mathrm{CN})]_{6}\) (b) \(\mathrm{Fe}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]_{3}\) (c) \(\mathrm{Fe}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]\) (d) \(\mathrm{Fe}_{3}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]_{2}\)

Ethanol and ethanal are distinguished by (a) Fehling's solution test (b) Tollen's reagent test (c) Iodoform test (d) Cerric ammonium nitrate

If \(\mathrm{N}\) and \(\mathrm{S}\) both are present in an organic compound during Lassaigne's test, both will change into (a) \(\mathrm{Na}_{2} \mathrm{~S}\) and \(\mathrm{NaCN}\) (b) NaSCN (c) \(\mathrm{Na}_{2} \mathrm{SO}_{3}\) and \(\mathrm{NaCN}\) (d) \(\mathrm{Na}_{2} \mathrm{~S}\) and \(\mathrm{NaCNO}\)

Which of the following statements are correct? (a) An organic compound is pure if mixed melting point is same. (b) Ethanol and water can be separated by azeotropic distillation because it forms azeotrope. (c) Impure aniline is purified by steam distillation as it is steam volatile. (d) Glycerol is purified by vaccuum distillation because it decomposes at its normal boiling point.

Which of the following will be blood red colour with \(\mathrm{FeCl}_{3}\) in sodium extract (Lassaigne extract)? (a) \(\mathrm{NH}_{2} \mathrm{CONH}_{2}\) (b) \(\mathrm{NH}_{2} \mathrm{CSNH}_{2}\) (c) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NHNH}_{2}\) (d) \(\mathrm{CH}_{3} \mathrm{C}=\mathrm{N}\)

\(\mathrm{HCOOH}\) and \(\mathrm{CH}_{3} \mathrm{COOH}\) can be distinguished by (a) Tollen's reagent (b) Fehling's solution (c) \(\mathrm{KMnO}_{4}\) (d) \(\mathrm{NaHCO}_{3}\)

Phenol and benzoic acid can be separated by (a) \(\mathrm{NaHCO}_{3}\) (b) \(\mathrm{NaOH}\) solution (c) \(\mathrm{FeCl}_{3}\) solution (d) All of these

The desiccants used for absorbing water during Liebig's method for estimation of carbon and hydrogen are (a) anhydrous \(\mathrm{CaCl}_{2}\) (b) anhydrous \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) (c) \(\mathrm{Mg}\left(\mathrm{ClO}_{4}\right)_{2}\) (d) \(\mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}\)

Anthracene can be purified by (a) Distillation (b) Sublimation (c) Filtration (d) Fractional distillation

\(\mathrm{KOH}\) can be used as a drying agent for (a) amines (b) phenols (c) acids (d) esters

Which of the following organic compounds will give white precipitate with \(\mathrm{AgNO}_{3} ?\) (a) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{3}{\underline{\phantom{xx}}}^{+} \mathrm{Cl}^{-}\) (b) \(\mathrm{NaCl}\) (c) \(2,4,6\) -trinitro chlorobenzene (d) Benzyl chloride

Silver salt method is used to determine molecular weight of (a) organic acids (b) organic bases (c) both acids and bases (d) none of these

Which of the following reactions occur during the detection of nitrogen in organic substances by Lassaigne's test? (a) \(\mathrm{Na}+\mathrm{C}+\mathrm{N} \longrightarrow \mathrm{NaCN}\) (b) \(\mathrm{FeSO}_{4}+6 \mathrm{NaCN} \longrightarrow \mathrm{Na}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]+\mathrm{Na}_{2} \mathrm{SO}_{4}\) (c) \(3 \mathrm{Na}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]+2 \mathrm{Fe}_{2}\left(\mathrm{SO}_{4}\right)_{3} \longrightarrow \mathrm{Fe}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]_{3}+6 \mathrm{Na}_{2} \mathrm{SO}_{4}\) (d) None of these

Which of the following observations is correct and is used in the identification of carboxylic acids? (a) Carboxylic acids liberate \(\mathrm{CO}_{2}\) gas from \(\mathrm{NaHCO}_{3}\) solution. (b) They produce fruity smell of esters when heated with alcohol in presence of Conc. \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (c) Both (a) and (b) (d) Iodoform test

Compound A reacts with \(\mathrm{CHCl}_{3}\) and KOH and gives an offensive smelling compound. A can be (a) Primary aliphatic amine (b) Primary aromatic amine (c) Secondary amine (d) Tertiary amine

An organic compound is heated with \(\mathrm{HNO}_{2}\) at \(0^{\circ} \mathrm{C}\) and then the resulting solution is added to a solution of \(\beta\) -naphthol whereby a brilliant red dye is produced. The observations indicate that the compound possesses (a) \(-\mathrm{NO}_{2}\) group (b) \(-\mathrm{CONH}_{2}\) group (c) aromatic \(\mathrm{NH}_{2}\) group (d) aliphatic \(\mathrm{NH}_{2}\) group

An organic compound contains \(\mathrm{C}, \mathrm{H}, \mathrm{N}, \mathrm{S}\) and \(\mathrm{Cl}\). For the detection of chlorine, the sodium extarct of the compound is first heated with a few drops of concentrated \(\mathrm{HNO}_{3}\) and then \(\mathrm{AgNO}_{3}\) is added to get a white ppt. of \(\mathrm{AgCl}\). The digestion with \(\mathrm{HNO}_{3}\) before the addition of \(\mathrm{AgNO}_{3}\) is (a) to prevent the formation of \(\mathrm{NO}_{2}\) (b) to create a common ion effect (c) to convert \(\mathrm{CN}\) - and \(\mathrm{S}^{2-}\) to volatile \(\mathrm{HCN}\) and \(\mathrm{H}_{2} \mathrm{~S}\), or else they will interfere with the test forming \(\mathrm{AgCN}\) or \(\mathrm{Ag}_{2} \mathrm{~S}\) (d) to prevent the hydrolysis of \(\mathrm{NaCN}\) and \(\mathrm{Na}_{2} \mathrm{~S}\)

and \(\mathrm{CH}_{3} \mathrm{CHO}\) can be distinguished by. (a) Tollen's test (b) Benedict's test (c) Iodoform test (d) 2,4 -DNP test

Rectified spirit contains (a) \(95.6\) per cent ethanol and \(4.4\) per cent methanol (b) 100 per cent ethanol (c) \(95.6\) per cent ethanol and \(4.4\) per cent water (d) \(95.6\) per cent ethanol and \(4.4\) per cent benzene

Acetic acid and \(\mathrm{CH}_{3} \mathrm{COCl}\) can be distinguished by (a) \(\mathrm{NaHCO}_{3}\) test (b) Na metal test (c) Ester formation test (d) \(\mathrm{Br}_{2}\) (aq.) test

Aniline can be separated from phenol using (a) \(\mathrm{NaHCO}_{3}\) (b) \(\mathrm{NaNO}_{2}+\mathrm{HCl}\) at \(0^{\circ} \mathrm{C}\) (c) \(\mathrm{NaCl}\) (d) Acidified \(\mathrm{KMnO}_{4}\)

Isolation of essential oils from flowers, etc. is done by (a) Steam disitllation (b) Distillation (c) Fractional distillation (d) Distillation under reduced pressure

Which of the following is steam volatile? (a) o-nitrophenol (b) \(\mathrm{p}\) -nitrophenol (c) \(\mathrm{p}\) -hydroxy benzaldehyde (d) Ethanol

Calculate weight of aniline distilled if weight of water distilled is \(100 \mathrm{~g}\) when \(P_{\text {organk compound }}=100 \mathrm{~mm}\) and \(P_{\mathrm{H}_{2} \mathrm{O}}=200 \mathrm{~mm}\). (a) \(250 \mathrm{~g}\) (b) \(258 \mathrm{~g}\) (c) \(100 \mathrm{~g}\) (d) \(25.8 \mathrm{~g}\)

Steam distillation is based on (a) Dalton's law of partial pressures (b) Graham's law of diffusion (c) Raoult's law of non-volatile solute (d) None of these

Which of the following cannot be separated by steam distillation? (a) Nitrobenzene (b) Essential oil (c) Aniline (d) Glycerol

Disodium pentacyanonitrosyl ferrate reagent gives purple colour when which of the following element is present? (a) \(\mathrm{N}\) (b) \(\mathrm{Cl}\) (c) \(\mathrm{F}\) (d) S

Phenol + Phthalic anhydride \(\frac{\text { Conc. } \mathrm{H}_{2} \mathrm{sO}_{4}}{\text { fiusion }}{\longrightarrow} \mathrm{B}\). B gives which of the following colour in alkaline medium? (a) Yellow (b) Colourless (c) Pink (d) Violet

To separate a mixture of amines from each other, one should follow (a) Beckmann's method (b) Hinsberg's method (c) Zeisel's method (d) Victor Meyer's Method

Phenol can be distiguished from ethanol by (a) Tollen's reagent (b) Benedict's reagent (c) \(\mathrm{FeCl}_{3}\) (d) Schiff 's base

\(\mathrm{p}-\mathrm{Cl}-\mathrm{C}_{6} \mathrm{H}_{4} \mathrm{NH}_{2}\) and \(\mathrm{PhNH}_{3}+\mathrm{Cl}^{-}\) can be distinguished by (a) \(\mathrm{NaOH}\) (b) \(\mathrm{AgNO}_{2}\) (c) \(\operatorname{LiAlH}_{4}\) (d) \(\mathrm{Zn}\)