JEE Main Previous Year Questions (2021-22): Practical Organic Chemistry | 35 Years Chapter wise Previous Year Solved Papers for JEE PDF Download

Q.1. The weight percentage of hydrogen in Q, formed in the following reaction sequence, is ________.          (JEE Advanced 2022)
[Given: Atomic mass of H = 1, C = 12, N = 14, O = 16, S = 32, Cl = 35]

Ans. 1.30 and 1.32

Q.2. Consider the following reaction.
On estimation of bromine in 1.00 g of R using Carius method, the amount of AgBr formed (in g) is ___________.
[Given: Atomic mass of H = 1, C = 12, O = 16, P = 31, Br = 80, Ag = 108]            (JEE Advanced 2022)

Ans. 1.49 and 1.51

Q.3. In bromination of Propyne, with Bromine, 1, 1, 2, 2-tetrabromopropane is obtained in 27% yield. The amount of 1, 1, 2, 2-tetrabromopropane obtained from 1 g of Bromine in this reaction is ___________ × 10⁻¹ g. (Nearest integer)
(Molar Mass : Bromine = 80 g/mol)          (JEE Main 2022)

Ans. 3

2 moles Br₂ ≡ 1 mole 1,1,2,2-tetrabromopropane 1/160 mole Br₂
 mole 1,1,2,2-tetrabromopropane
But yield of reaction is only 27%
Moles of 1,1,2,2-tetrabromopropane

Molar mass of 1,1,2,2-tetrabromopropane = 360 g
Mass of 1,1,2,2-tetrabromopropane

Q.4. A sample of 0.125 g of an organic compound when analyzed by Duma's method yields 22.78 mL of nitrogen gas collected over KOH solution at 280 K and 759 mmHg. The percentage of nitrogen in the given organic compound is __________. (Nearest integer)
Given : (a) The vapour pressure of water of 280 K is 14.2 mmHg.
(b) R=0.082 L atm K⁻¹ mol⁻¹                (JEE Main 2022)

Ans. 22 
P_actual = 759 − 14.2 = 744.8mm Hg

= 0.000971 mol
Mass of N₂ = 0.02719gm
Percentage of nitrogen

Q.5. In the below reaction, 5 g of toluene is converted into benzaldehyde with 92% yield. The amount of benzaldehyde produced is ______________ × 10⁻² g. (Nearest integer)          (JEE Main 2022)

Ans. 530

Moles = 592
Moles of benzaldehyde produced

∴ Mass of benzaldehyde formed
= 0.05 × 106
=5.3 g
= 530 × 10^-2   

Q.6. The separation of two coloured substances was done by paper chromatography. The distances travelled by solvent front, substance A and substance B from the base line are 3.25 cm, 2.08 cm and 1.05 cm, respectively. The ratio of R_f values of A to B is _____________.          (JEE Main 2022)

Ans. 2

Q.7. While estimating the nitrogen present in an organic compound by Kjeldahl's method, the ammonia evolved from 0.25 g of the compound neutralized 2.5 mL of 2MH₂SO₄. The percentage of nitrogen present in organic compound is ______________.          (JEE Main 2022)

Ans. 56
NH₃ gas is neutralized by 2.5 mL of 2M H₂SO₄ 
∴ Moles of NH3 neutralized =2.5 × 2 × 2 millimole moles
=10 × 10⁻³ moles
∴ Weight of N present in the compound will be
=10 × 10⁻³ × 14 = 0.14 g
∴% of ' N ' in compound

Q.8. An organic compound with 51.6% sulfur is heated in a Carius tube. The amount of this compound which will form 0.752 g of barium sulphate is ___________ × 10⁻¹ g.
(Given molar mass of barium sulphate 233 g mol⁻¹) (Nearest integer).          (JEE Main 2022)

Ans. 2
233 g BaSO₄ contains = 32 g sulphur




 ≈ 2 x 10^-1 g

Q.9. How many of the given compounds will give a positive Biuret test ____________ ?
Glycine, Glycylalanine, Tripeptide, Biuret          (JEE Main 2022)

Ans. 2

Q.10. 0.25 g of an organic compound containing chlorine gave 0.40 g of silver chloride in Carius estimation. The percentage of chlorine present in the compound is ___________. [in nearest integer]
(Given : Molar mass of Ag is 108 g mol⁻¹ and that of Cl is 35.5 g mol⁻¹)          (JEE Main 2022)

Ans. 40
Given, weight of organic compound = 0.25 g
Moles of AgCl = 0.4/M
Molecular mass of AgCl (M) = 143.5 gm
∴ Moles of AgCl = 0.4/143.5

Mass % of Cl in the organic compound =35.5×0.4143.50.25×35.5
=39.58

= 39.58

Q.11. Kjeldahl's method was used for the estimation of nitrogen in an organic compound. The ammonia evolved from 0.55 g of the compound neutralised 12.5 mL of 1 M H₂SO₄ solution. The percentage of nitrogen in the compound is _____________. (Nearest integer)          (JEE Main 2022)

Ans. 64

Q.12. Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Phenolphthalein is a pH dependent indicator, remains colourless in acidic solution and gives pink colour in basic medium.
Reason R: Phenolphthalein is a weak acid. It doesn't dissociate in basic medium.
In the light of the above statements, choose the most appropriate answer from the options given below.          (JEE Main 2021)
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is NOT the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

Ans. c
Phenolphthalein is a pH dependent indicator. It is a weak acid which is colourless in the acidic solution but gives pink colour in basic medium. The pink colour is due to its conjugate form. Therefore, assertion (A) is true but Reason (R) is false.

Q.13. Which technique among the following, is most appropriate in separation of a mixture of 100mg of p-nitrophenol and picric acid ?          (JEE Main 2021)
(a) Steam distillation
(b) 2-5 ft long column of silica gel
(c) Sublimation
(d) Preparative TLC (Thin Layer Chromatography)

Ans. d
Thin layer chromatography is a technique used to isolate non-volatile mixtures.
Hence, mixture of p-nitrophenol and Picric acid is separated by TLC.

Q.14. In base vs. acid titration, at the end point methyl orange is present as          (JEE Main 2021)
(a) quinonoid form
(b) heterocyclic form
(c) phenolic form
(d) benzenoid form

Ans. a

Q.15. Match List I with List II
Choose the correct answer from the options given below :          (JEE Main 2021)
(a) (A)−(II),(B)−(IV),(C)−(I),(D)−(III)
(b) (A)−(II),(B)−(I),(C)−(IV),(D)−(III)
(c) (A)−(III),(B)−(IV),(C)−(I),(D)−(II)
(d) (A)−(III),(B)−(I),(C)−(IV),(D)−(II)

Ans. c
Here, we have to match the reactions with their correct catalyst :




∴ Option (C) is correct option.

Q.16. During the qualitative analysis of salt with cation y²⁺, addition of a reagent (X) to alkaline solution of the salt gives a bright red precipitate. The reagent (X) and the cation (y²⁺) present respectively are :          (JEE Main 2021)
(a) Dimethylglyoxime and Ni²⁺
(b) Dimethylglyoxime and Co²⁺
(c) Nessler's reagent and Hg²⁺
(d) Nessler's reagent and Ni²⁺

Ans. a
On addition of dimethylglyoxime to alkaline solution of Ni⁺², a bright red ppt. is obtained.
Ni⁺² + 2dmg → [Ni(dmg)₂]⁺² (Bright red ppt)

Q.17. Phenol on reaction with dilute nitric acid, gives two products. Which method will be most efficient for large scale separation?          (JEE Main 2021)
(a) Chromatographic separation
(b) Fractional Crystallisation
(c) Steam distillation
(d) Sublimation

Ans. c

o-Nitrophenol and p-Nitrophenol can be easily separated by steam distillation.

Q.18. Given below are two statements :
Statement I : In 'Lassaigne's Test', when both nitrogen and sulphur are present in an organic compound, sodium thiocyanate is formed.
Statement II : If both nitrogen and sulphur are present in an organic compound, then the excess of sodium used in sodium fusion will decompose the sodium thiocyanate formed to give NaCN and Na₂S.
In the light of the above statements, choose the most appropriate answer from the options given below :          (JEE Main 2021)
(a) Both Statement I and Statement II are correct.
(b) Both Statement I and Statement II are incorrect.
(c) Statement I is correct but Statement II is incorrect.
(d) Statement I is incorrect but Statement II is correct.

Ans. a

Q.19. Sodium stearate CH₃(CH₂)₁₆COO⁻Na⁺ is an anionic surfactant which forms micelles in oil.
Choose the correct statement for it from the following :          (JEE Main 2021)
(a) It forms spherical micelles with CH₃(CH₂)₁₆ - group pointing towards the centre of sphere.
(b) It forms non-spherical micelles with -COO− group pointing outwards on the surface.
(c) It forms spherical micelles with CH₃(CH₂)₁₆ - group pointing outwards on the surface of sphere
(d) It forms non-spherical micelles with CH₃(CH₂)₁₆ - group pointing towards the centre.

Ans. a
Forms spherical micelles with CH₃(CH₂)₁₆ group pointing towards the centre of sphere.

Q.20. When silver nitrate solution is added to potassium iodide solution then the sol produced is :          (JEE Main 2021)
(a) AgI / I⁻
(b) AgI / Ag⁺
(c) KI / NO₃⁻
(d) AgNO₃ / NO₃⁻ 

Ans. a

Q.21. Which purification technique is used for high boiling organic liquid compound (decomposes near its boiling point)?          (JEE Main 2021)
(a) Simple distillation
(b) Steam ditillation
(c) Fractional distillation
(d) Reduced pressure distillation

Ans. d
Reduced pressure distillation or vacuum distillation is used for the purification of high boiling organic liquids which decomposes at or below their boiling point.

Q.22. For below chemical reactions, identify the correct statement from the following :          (JEE Main 2021)
(a) Both compound 'A' and compound 'B' are dicarboxylic acids
(b) Both compound 'A' and compound 'B' are diols
(c) Compound 'A' is diol and compound 'B' is dicarboxylic acid
(d) Compound 'A' is dicarboxylic acid and compound 'B' is diol

Ans. d

Q.23. Nitrogen can be estimated by Kjeldahl's method for which of the following compound?          (JEE Main 2021)
(a)
(b)
(c)

(d)   

Ans. d
Kjeldahl’s method can’t be used for compounds containing nitro or azo groups.
Also for compounds containing nitrogen in the ring, Kjeldahl’s method can’t be used.

Q.24. Given below are two statements :
Statement I : Retardation factor (Rf) can be measured in meter/centimeter.
Statement II : Rf value of a compound remains constant in all solvents.
Choose the most appropriate answer from the options given below :          (JEE Main 2021)
(a) Statement I is true but statement II is false
(b) Statement I is false but statement II is true
(c) Both statement I and statement II are true
(d) Both statement I and statement II are false

Ans. d
Retardation factor (Rf) is the ratio of the distance moved by the substance from the baseline to the distance moved by the solvent from the baseline. So, it is dimensionless. The distance moved by the substance is due to the adsorption of the substance on the stationary phase. It does not depend on the nature of the solvent. But the distance moved by the solvent will change with the nature of the solvent. Therefore, Rf will vary with the change in the solvent.
So, both the statements are false.

Q.25. In chromotography technique, the purification of compound is independent of :          (JEE Main 2021)
(a) Solubility of the compound
(b) Mobility or flow of solvent system
(c) Physical state of the pure compound
(d) Length of the column or TLC plate

Ans. c
In chromatography technique, the purification of a compound is independent of the physical state of the pure compound.

Q.26. On treating a compound with warm dil. H₂SO₄, gas X is evolved which turns K₂Cr₂O₇ paper acidified with dil. H₂SO₄ to a green compound Y. X and Y respectively are :          (JEE Main 2021)
(a) X = SO₂, Y = Cr₂O₃
(b) X = SO₃, Y = Cr₂(SO₄)₃
(c) X = SO₃, Y = Cr₂O₃
(d) X = SO₂, Y = Cr₂(SO₄)₃ 

Ans. d
SO₂ + K₂Cr₂O₇ + dil. H₂SO₄ → SO₃ + Cr₂(SO₄)₃ (green)

Q.27. Given below are two statements :
Statement I: Colourless cupric metaborate is reduced to cuprous metaborate in a luminous flame.
Statement II : Cuprous metaborate is obtained by heating boric anhydride and copper sulphate in a non-luminous flame.
In the light of the above statements, choose the most appropriate answer from the options given below.          (JEE Main 2021)
(a) Statement I is true but Statement II is false
(b) Statement I is false but Statement II is true
(c) Both Statement I and Statement II are false
(d) Both Statement I and Statement II are true

Ans. c
In presence of luminous flame, blue cupric metaborate is reduced to colourless cuprous metaborate.

If non-luminous flame is present in reaction, cupric metaborate is obtained by heating boric anhydride with copper sulphate.

So, both statements are false.

Q.28. The transformation occurring in Duma's method is given below :

The value of y is ______________. (Integer answer)          (JEE Main 2021)

Ans. 7

On balancing

On comparing
y = 7

Q.29. The number of moles of CuO, that will be utilized in Dumas method for estimation nitrogen in a sample of 57.5 g of N, N-dimethylaminopentane is _____________ × 10⁻². (Nearest integer)          (JEE Main 2021)

Ans. 1125
Moles of N in N, N - dimethylaminopentane = (57.5/115) = 0.5 mol

Q.30. In Duma's method of estimation of nitrogen, 0.1840 g of an organic compound gave 30 mL of nitrogen collected at 287 K and 758 mm of Hg pressure. The percentage composition of nitrogen in the compound is __________. (Round off to the Nearest Integer). [Given : Aqueous tension at 287 K = 14 mm of Hg]          (JEE Main 2021)

Ans. 19
Aqueous tension at 287 K = 14 mm of Hg.
Hence actual pressure = (758 – 14)
= 744 mm of Hg.

= 1.246 × 10⁻³ mol mass of
mass of N₂ = 1.246 x 10^-3 x 28

Q.31. Using the provided information in the following paper chromatogram :
Fig : Paper chromatography for compounds A and B.The calculated Rf value of A ________× 10^-1.          (JEE Main 2021)

Ans. 4

On chromatogram distance travelled by compound is = 2 cm
Distance travelled by solvent = 5 cm

Q.32. 1.86 g of aniline completely reacts to form acetanilide. 10% of the product is lost during purification. Amount of acetanilide obtained after purification (in g) is __________ × 10⁻².          (JEE Main 2021)

Ans. 243

Given, weight = 18.6 g
Here, 1 mole of aniline gives 1 mole of acetanilide
∴ mole of aniline = mole of acetanilide


But efficiency of reaction is 90% only.
Hence, mass of acetanilide produced

x = 243