Practical Organic Chemistry problems for Jee

Detection of Carbon and Hydrogen
Liebig’s Test

Sodium nitroprusside test:
The one portion of the extract, a few drops sodium
nitroprusside are added. The appearance of violet colouration
indicates sulphur.
Test For Sulphur

Test for unsaturation
Addition of bromine to an alkene results in the formation
of vicinal dibromide. The reddish orange colour of the
solution of bromine in carbon tetrachloride disappears
on reaction with an alkene
Bromine water Test:

Test for unsaturation
Alkenes decolourise the neutral/alkaline KMnO4
solution
and vicinal glycols are formed (Bayer’s test).
Bayer’s Test

Test for (-OH) Alcoholic group
Alcoholic compounds on reaction with ceric ammonium
nitrate give a red colouration due to the formation of a
complex.
Ceric ammonium nitrate Test

Test for (-OH) Alcoholic group
Tertiary alcohols react almost instantaneously, secondary
alcohols react in about 1-5 minutes and primary alcohols react
very slowly. The reaction may take 10 minutes to several days.
Lucas Test

Test for Phenols
Ferric Chloride Test
Phenols give coloured complex with neutral ferric
chloride solution.

Test for Phenols
Phthalein dye test
Phenols condense with phthalic anhydride in the presence of
concentrated H2
SO4
, Phenol condenses to give phenolphthalein
which gives a dark pink colour with NaOH solution.

Test for Phenols
Phthalein dye test

Test for Phenols
Libermann’s Reaction
While phenol is reacted with NaNO2
and concentrated
H2
SO4
, it provides a deep green colour which changes
to red on dilution with water. while generated alkaline
along with NaOH, blue colour is restored.

Test for Phenols
Libermann’s Reaction

Test for Phenols
Bromine Water Test
Aqueous or alcoholic solution of the organic
compound is mixed with bromine water. A yellowish
white precipitate is formed.

Test for Carbonyl Group
On reaction with 2,4-dinitrophenylhydrazine (2,4-DNP), they form the
respective 2,4–dinitrophenyl hydrazones.
2,4-DNP Test

Test for Carbonyl Group
This test is not given by aromatic ketones like acetophenone and
benzophenone. This is also not given by Pentan-3-one.
Sodium Bisulphite Test

Test for Aldehyde only
Both aliphatic and aromatic aldehydes give this test but
ketones do not respond to this test because like aldehydes they
are not good reducing agent.
Tollen’s Test

This test is given only by aliphatic aldehydes but not by
aromatic aldehydes
Fehling’s Test

Benedict modified the original Fehling’s test by using a single
solution which is more convenient for the test. Benedict’s
solution is more stable than Fehling’s reagent and can be stored
for a long time. It is an alkaline solution containing a mixture of
copper sulphate and sodium citrate (2Na3
C6
H5
O7
.11H2
O).
Benedicts test

Test for COOH Group
RCOOH + NaHCO3
→ RCOONa + H2
O + CO2
↑
Sodium Bicarbonate Test

Test for COOH Group
Ester Test or Fruity Smell Test

Test for Amines
Carbylamine Reaction
Aliphatic as well as aromatic primary amines give
carbylamine test in which an amine is heated with
chloroform.

Test for Amines
Nitrous acid Test

Test for Amines
Azo dye test
Aromatic primary amines can be confirmed by azo dye test.
Primary amine e.g. aniline reacts with nitrous acid generated in
situ by the reaction of sodium nitrite with HCl at 0–5°C to
produce diazonium salt. This couples with β-naphthol to give a
scarlet red dye, which is sparingly soluble in water.

Test for Amines
Hinsberg’s Test
Benzenesulphonyl chloride (C6
H5
SO2
Cl), which is also known
as Hinsberg’s reagent, reacts with primary and secondary
amines to form sulphonamides

Test for Amines
Hinsberg’s Test (Primary Amines)

Test for Amines
Insoluble in alkali
Hinsberg’s Test (Secondary Amines)

Biuret Test
The biuret test is a chemical test that can be used to see if an
analyte has peptide bonds or not. As a result, the biuret test may
be used to figure out how much protein is in the analyte. In this
test, the presence of peptides induces the copper (II) ion to form
pale purple (or mauve) coordination complexes (when the
solution is sufficiently alkaline).

Molisch’s Test
In Molisch’s test, the carbohydrate (if present) undergoes
dehydration upon the introduction of concentrated hydrochloric or
sulphuric acid, resulting in the formation of an aldehyde. This
aldehyde undergoes condensation along with two phenol-type
molecules (such as α-naphthol, resorcinol, and thymol), resulting
in the formation of a purple or reddish-purple coloured complex.

Seliwanoff’s Test
Seliwanoff’s test is used to distinguish aldoses from ketoses. On
treatment with a concentrated Acid, ketoses are dehydrated more
rapidly to give furfural derivatives and on condensation with
resorcinol give cherry red complex. The test will be answered by
fructose, sucrose and other keto containing carbohydrates. If the
reaction is allowed for a longer time (more than 10 minutes),
aldoses also may produce positive results. Seliwanoff’s test is
often considered to be a test for ketohexoses in carbohydrates.
● Seliwanoff’s reagent: Add 0.05% resorcinol
(m-hydroxybenzene) in 3 N HCl. Dissolve 50 mg
resorcinol in 33 ml concentrated HCl and make it 100 ml
with water.

Barfoed Test
● The Barfoed’s test is used to differentiate reducing monosaccharide
from a disaccharide sugar. The reaction is conducted in a slightly acidic
medium.
● A mixture of ethanoic (acetic) acid and copper(II) acetate, is added to
the test solution and boiled.
● Reducing monosaccharides react with Bedford’s reagent much faster
than disaccharides and produce a copious amount of red precipitate of
copper (I) oxide within three minutes. Disaccharide sugars as they are
weaker reducing agents, react at a slower rate and so do not form red
precipitate even for ten minutes. Some hydrolysis of disaccharides may
lead to trace precipitates which tends to adhere to the walls of the test
tube.

Ninhydrin Test
The ninhydrin test is a chemical test which is used to check whether a
given analyte contains amines or α-amino acids. In this test, ninhydrin
(a chemical compound with the formula C9
H6
O4
; IUPAC name:
2,2-dihydroxyindane-1,3-dione) is added to a test solution of the
analyte. The development of a deep blue colour indicates the presence
of ammonia, primary/secondary amines, or amino acids in the
analyte.

Xanthoproteic Test
Xanthoproteic test is a biochemical test for the detection of amino acids
containing phenolic or indolic groups like phenylalanine, tyrosine, and
tryptophan (aromatic amino acids). The Xanthoproteic test is based on the
fact that aromatic groups in the amino acids are nitrated by heating with
concentrated HNO3 to yield intensely yellow-colored nitro derivative. On the
addition of alkali, however, the residue turns orange due to the formation of
a salt of the tautomeric form of the nitro compound. Benzene
ring-containing amino acids like phenylalanine don’t give a positive test to
this test because the phenyl group in phenylalanine is very stable, which
doesn’t react with nitric acid in the conditions of this test.

Estimation of Carbon and Hydrogen:

Estimation of Sulphur and Phosphorus

Q- The tests performed on compound X and their inferences are :
Compound ‘X’ is JEE Main 2019
Test Inference
(a) 2, 4 - DNP test Coloured precipitate
(b) Iodoform test Yellow precipitate
(c) Azo-dye test No dye formation
A B
C D

Q- The correct match between Item I and Item II is
A
B
C
D
(A) → (Q); (B) → (S); (C) → (P)
(A) → (R); (B) → (Q); (C) → (P)
(A) → (Q); (B) → (S); (C) → (R)
(A) → (R); (B) → (S); (C) → (Q)
JEE Main 2019
Item I Item II
(A) Ester test (P) Tyr
(B) Carbylamine test (Q) Asp
(C) Phthalein dye test (R) Ser
(S) Lys

Q- The organic compound that gives following qualitative analysis is
JEE Main 2019
Test Inference
(a) Dil.HCl Insoluble
(b) NaOH solution Soluble
(c) Br2
/water Decolourization
A B
C D

Q- Which of the following tests cannot be used for identifying amino acids?
A
B
C
D
Barfoed test
Biuret test
Xanthoproteic test
Ninhydrin test
JEE Main 2019

Solution:
Barfoed test is used for carbohydrate to check reducing nature of sugar.

Q- Fructose and glucose can be distinguished by:
A
B
C
D
Fehling's test
Seliwanoff's test
Barfoed's test
Benedict's test
JEE Main 2019

Solution:
Seliwanoff's test is used to distinguish aldose and ketose.

Q- The peptide that gives positive ceric ammonium nitrate and carbylamine tests
is
A
B
C
D
Ser - Lys
Lys - Asp
Gln - Asp
Asp - Gln
JEE Main 2019

Solution:
Ceric ammonium nitrate test is given by alcohol. Only serine(ser) contain —OH group.

Q- Match the following :
A
B
C
D
(i) - (b), (ii) - (d), (iii) - (e), (iv) - (a)
(i) - (d), (ii) - (c), (iii) - (e), (iv) - (a)
(i) - (b), (ii) - (a), (iii) - (c), (iv) - (d)
(i) - (d), (ii) - (c), (iii) - (b), (iv) - (e)
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Test / Method Reagent
(i) Lucas Test (a)C6
H5
SO2
Cl/aq. KOH
(ii) Dumas method (b) HNO3
/ AgNO3
(iii) Kjeldahl’s method (c) CuO/CO2
(iv) Hinsberg test (d) Conc. HCl and ZnCl2
(e) H2
SO4

Solution:
Lucas Test - Conc. HCl/ZnCl2
Dumas method - CuO/CO2
Kjeldahl’s method - H2
SO4
Hinsberg test - C6
H5
SO2
Cl/aq. KOH

Q- An organic compound ‘A’ (C9
H10
O) when treated with conc. HI undergoes
cleavage to yield compounds ‘B’ and ‘C’ . ‘B’ gives yellow precipitate with AgNO3
where as ‘C’ tautomerizes to ‘D’. ‘D’ gives positive iodoform test. ‘A’ could be
A
B
C
D
JEE Main 2020

Q- A chemist has 4 samples of artificial sweetener A, B, C and D. To identify these
samples, he performed certain experiments and noted the following observations :
(i) A and D both form blue-violet colour with ninhydrin.
(ii) Lassaigne extract of C gives positive AgNO3
test and negative Fe4
[Fe(CN)6
]3
test.
(iii) Lassaigne extract of B and D gives positive sodium nitroprusside test.
Based on these observations which option is correct?
A
B
C
D
A : Aspartame; B : Alitame; C : Saccharin; D : Sucralose
A : Saccharin; B : Alitame; C : Sucralose; D : Aspartame
A : Alitame; B : Saccharin; C : Aspartame; D : Sucralose
A : Aspartame; B : Saccharin; C : Sucralose; D : Alitame
JEE Main 2020

Solution:
● Ninhydrin test is specific for amino acids.
● Both aspartame and alitame contains amino acids.
● Alitame is sulphur containing compound thats why gives sodium
nitroprusside test
● Saccharin also contains sulphur
● Sucralose contains chloro group thats why its Lassaigne extract
gives white ppt with AgNO3
.
∴ A = Aspartame, B = Saccharin C = Sucralose, D = Alitame.

Q- A, B and C are three biomolecules. The results of the tests performed on them
are given below
A, B and C are respectively
A
B
C
D
A = Lactose, B = Fructose, C = Alanine
A = Lactose, B = Glucose, C = Alanine
A = Glucose, B = Fructose, C = Albumin
A = Lactose, B = Glucose, C = Albumin
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Molisch's Test Barfoed Test Biuret Test
A Positive Negative Negative
B Positive Positive Negative
C Negative Negative Positive

Solution:
- All carbohydrates give, Molisch’s test
- Barfoed test is specific for monosaccharide
- Biuret test is used for detecting the presence of peptide bonds

Q- Ceric ammonium nitrate and CHCl3
/alc. KOH are used for the identification of
functional groups present in ___ and __ respectively
A
B
C
D
Alcohol, phenol
Amine, phenol
Amine, alcohol
Alcohol, amine
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Q- 2, 4 - DNP test can be used to identify
A
B
C
D
Aldehyde
Amine
Ether
Halogens
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Q- An unsaturated hydrocarbon X on ozonolysis gives A. Compound A when
warmed with ammonical silver nitrate forms a bright silver mirror along the sides
of the test tube. The unsaturated hydrocarbon X is :
A
B
C
D
HC ≡ C ー CH2
ー CH3
CH3
ー C ≡ C ー CH3
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Q- An unsaturated hydrocarbon X on ozonolysis gives A. Compound A when
warmed with ammonical silver nitrate forms a bright silver mirror along the sides
of the test tube. The unsaturated hydrocarbon X is :
A
B
C
D
HC ≡ C ー CH2
ー CH3
CH3
ー C ≡ CーCH3
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Q- In Tollen's test for aldehyde, the overall number of electron(s) transferred to the
Tollen's reagent formula [Ag(NH3
)2
]+
per aldehyde group to form silver mirror is
____.
(Round off to the Nearest Integer).
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Q- In Tollen's test for aldehyde, the overall number of electron(s) transferred to the
Tollen's reagent formula [Ag(NH3
)2
]+
per aldehyde group to form silver mirror is
____.
(Round off to the Nearest Integer).
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Ans 2

Q- A reaction of benzonitrile with one equivalent CH3
MgBr followed by hydrolysis
produces a yellow liquid "P". The compound "P" will give positive ______.
A
B
C
D
Tollen's test
Schiff's test
Ninhydrin's test
lodoform test
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Q- Which one of the following tests used for the identification of functional groups
in organic compounds does not use copper reagent?
A
B
C
D
Seliwanoff’s test
Barfoed's test
Benedict's test
Biuret test for peptide bond
JEE Main 2021

Solution:
Seliwanoff’s test → Resorcinol dissolved in conc HCI.
All other test use copper based reagent.

Q- Which of the following compound is added to the sodium extract before
addition of silver nitrate for testing of halogens?
A
B
C
D
Hydrochloric acid
Sodium hydroxide
Ammonia
Nitric acid
JEE Main 2021

Solution:
The sodium fusion extract is acidified with nitric acid and then treated with silver nitrate.

Q- Match List-I with List-II
The correct match is:
A
B
C
D
(a)-(iii), (b)-(i), (c)-(iv), (d)-(ii)
(a)-(i), (b)-(iv), (c)-(iii), (d)-(ii)
(a)-(iii), (b)-(i), (c)-(ii), (d)-(iv)
(a)-(i), (b)-(ii), (c)-(iv), (d)-(iii)
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List-I Test/Reagents/ Observation(s) List-II Species detected
(a) Lassaigne's Test (i) Carbon
(b) Cu(II) oxide (ii) Sulphur
(c) Silver nitrate (iii) N, S, P, and halogen
(d) The sodium fusion extract gives black
precipitate with acetic acid and lead acetate
(iv) Halogen Specifically

Q-
Which among the following represent reagent ‘A’?
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A B
C D

Q- During halogen test, sodium fusion extract is boiled with concentrated HNO3
to
A
B
C
D
remove unreacted sodium
decompose cyanide or sulphide of
sodium
extract halogen from organic compound
maintain the pH of extract.
JEE Main 2022

Solution:
During test for halogen. if nitrogen or sulphur is also present in the compound, then
sodium fusion extract is first boiled with concentrated nitric acid to decompose cyanide
or sulphide of sodium formed during Lassaigne's test.

Q- The formula of the purple colour formed in Lassaigne's test for sulphur using
sodium nitroprusside is
A
B
C
D
NaFe[Fe(CN)6
]
Na[Cr(NH3
)2
(NCS)4
]
Na2
[Fe(CN)5
(NO)]
Na4
[Fe(CN5
)(NOS)]
JEE Main 2022

Solution:
Purple
S2-
+ [Fe(CN)5
NO]2-
→ [Fe(CN)5
(NOS)]4-

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Practical Organic Chemistry problems for Jee

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