Purification and Characterisation of Organic Compounds — JEE Main PYQs

Complete combustion of X g of an organic compound gave 0.25 g of $\mathrm{CO_2}$ and 0.12 g of $\mathrm{H_2O}$. If the % of carbon is 25% and of hydrogen is 4.89%, then X = _____ $\times 10^{-3}$ g. (Nearest integer)

(Molar mass of C, H and O are 12, 1 and 16 g mol$^{-1}$ respectively.)

2.0 g of a bromo hydrocarbon (X) was subjected to Carius analysis, gave 3.36 g of AgBr. The percentage of carbon in the compound (X) is 26.7%. Total number of carbon atoms in the empirical formula for compound (X) is ________. (Given molar mass in g mol$^{-1}$ H:1, C:12, Br : 80, Ag : 108)

In sulphur estimation, $2.0 \times 10^{-3}$ mol of an organic compound (X) (molar mass 76 $\mathrm{g\ mol^{-1}}$) gave 0.4813 g of barium sulphate (molar mass 233 $\mathrm{g\ mol^{-1}}$). The percentage of sulphur in the compound (X) is ___________ $\times 10^{-1}$ % (Nearest integer)

In an estimation of sulphur by Carius method 0.2 g of the substance gave 0.6 g of $\mathrm{BaSO_4}$. The percentage of sulphur in the substance is ________ %.

(Given molar mass in $\mathrm{g\ mol^{-1}}$ S : 32, $\mathrm{BaSO_4}$ : 231)

Match List - I with List - II.

	List - I (Purification technique)		List - II (Used to separate)
A.	Simple distillation	I.	Steam volatile compound
B.	Fractional distillation	II.	Two liquids with large difference in boiling points
C.	Steam distillation	III.	Liquid decomposing at its boiling point
D.	Distillation under reduced pressure	IV.	Two liquids with close boiling points

Choose the correct answer from the options given below :

$\mathrm{R_f}$ value for 2-methylpropene in a solvent system (Ethyl acetate + ether) is 0.42. 2-methylpropene is treated with dilute $\mathrm{H_2SO_4}$ to give major organic product (X). $\mathrm{R_f}$ value for (X) in the same solvent system under identical condition will be:

Given below are two statements :

Statement I : A mixture of $\mathrm{C_{12}H_{22}O_{11}}$ (sugar) and NaCl can be separated by dissolving sugar in alcohol, due to differential solubility.

Statement II : Rose essence from rose petals is seperated by steam distillation due to its high volatility and insolubility in $\mathrm{H_2O}$.

In the light of the above statements, choose the correct answer from the options given below :

Given below are two statements :

Statement I : Vapours of the liquid with higher boiling point condense before vapours of the liquid with lower boiling points in fractional distillation.

Statement II : The vapours rising up in the fractionating column become richer in high boiling component of the mixture.

In the light of the above statements, choose the correct answer from the options given below :

On complete combustion 1.0 g of an organic compound (X) gave 1.46 g of $\mathrm{CO_2}$ and 0.567 g of $\mathrm{H_2O}$. The empirical formula mass of compound (X) is __________ g.

(Given molar mass in $\mathrm{g\ mol^{-1}}$ C : 12, H : 1, O : 16)

Match List - I with List - II.

List - I (Purification technique)	List - II (Mixture of organic compounds)
(A) Distillation (simple)	(I) Diesel + Petrol
(B) Fractional distillation	(II) Aniline + Water
(C) Distillation under reduced pressure	(III) Chloroform + Aniline
(D) Steam distillation	(IV) Glycerol + Spent-lye

Choose the correct answer from the options given below :

In Dumas' method for estimation of nitrogen, 0.5 gram of an organic compound gave 60 mL of nitrogen collected at 300 K temperature and 715 mm Hg pressure. The percentage composition of nitrogen in the compound (Aqueous tension at 300 K = 15 mm Hg) is __________%.

0.5 g of an organic compound on combustion gave 1.46 g of $\mathrm{CO_2}$ and 0.9 g of $\mathrm{H_2O}$. The percentage of carbon in the compound is __________. (Nearest integer)

[Given : Molar mass (in g mol$^{-1}$) C : 12, H : 1, O : 16]

During estimation of nitrogen by Dumas' method of compound X (0.42 g)

[Figure: structure of X — piperazine, a six-membered saturated ring with N–H groups at positions 1 and 4 ($\mathrm{C_4H_{10}N_2}$)]

__________ mL of $\mathrm{N_2}$ gas will be liberated at STP. (nearest integer)

(Given molar mass in g mol$^{-1}$ : C : 12, H : 1, N : 14)

In Dumas' method for estimation of nitrogen 0.4 g of an organic compound gave 60 mL of nitrogen collected at 300 K temperature and 715 mm Hg pressure. The percentage composition of nitrogen in the compound is

(Given : Aqueous tension at 300 K = 15 mm Hg)

Match List - I with List - II.

List - I (Separation of)	List - II (Separation Technique)
(A) Aniline from aniline-water mixture	(I) Simple distillation
(B) Glycerol from spent-lye in soap industry	(II) Fractional distillation
(C) Different fractions of crude oil in petroleum industry	(III) Distillation at reduced pressure
(D) Chloroform-Aniline mixture	(IV) Steam distillation

Choose the correct answer from the options given below :

An organic compound weighing 500 mg, produced 220 mg of $\mathrm{CO_2}$, on complete combustion. The percentage composition of carbon in the compound is ________%. (nearest integer)

(Given molar mass in g mol$^{-1}$ of C:12, O:16)

Mixture of 1 g each of chlorobenzene, aniline and benzoic acid is dissolved in 50 mL ethyl acetate and placed in a separating funnel. 5 M NaOH (30 mL) was added in the same funnel. The funnel was shaken vigorously and then kept aside. The ethyl acetate layer in the funnel contains :

In Dumas' method 292 mg of an organic compound released 50 mL of nitrogen gas ($\mathrm{N_2}$) at 300 K temperature and 715 mm Hg pressure. The percentage composition of 'N' in the organic compound is __________% (Nearest integer)

(Aqueous tension at 300 K = 15 mm Hg)

On combustion 0.210 g of an organic compound containing C, H and O gave 0.127 g $\mathrm{H_2O}$ and 0.307 g $\mathrm{CO_2}$. The percentages of hydrogen and oxygen in the given organic compound respectively are:

In Carius method for estimation of halogens, 180 mg of an organic compound produced 143.5 mg of AgCl. The percentage composition of chlorine in the compound is ________ %.

(Given : molar mass in $\mathrm{g\ mol^{-1}}$ of Ag : 108, Cl : 35.5)

Given below are two statements :

Statement (I) : Nitrogen, sulphur, halogen and phosphorus present in an organic compound are detected by Lassaigne's Test.

Statement (II) : The elements present in the compound are converted from covalent form into ionic form by fusing the compound with Magnesium in Lassaigne's test.

In the light of the above statements, choose the correct answer from the options given below :

Given below are two statements:

Statement I: In Lassaigne's test, the covalent organic molecules are transformed into ionic compounds.

Statement II: The sodium fusion extract of an organic compound having N and S gives prussian blue colour with $\mathrm{FeSO_4}$ and $\mathrm{Na_4[Fe(CN)_6]}$

In the light of the above statements, choose the correct answer from the options given below

During "S" estimation, 160 mg of an organic compound gives 466 mg of barium sulphate. The percentage of Sulphur in the given compound is _____ %.

(Given molar mass in g mol$^{-1}$ of Ba : 137, S : 32, O : 16)

0.01 mole of an organic compound (X) containing 10% hydrogen, on complete combustion produced 0.9 g $\mathrm{H_2O}$. Molar mass of (X) is ________ $\mathrm{g\ mol^{-1}}$.

Given below are two statements I and II.

Statement I: Dumas method is used for estimation of "Nitrogen" in an organic compound.

Statement II: In Dumas method, the organic compound is heated with concentrated $\mathrm{H_2SO_4}$ to form ammonium sulphate.

In the light of the above statements, choose the correct answer from the options given below:

In Carius method of estimation of halogen, 0.25 g of an organic compound gave 0.15 g of silver bromide (AgBr). The percentage of Bromine in the organic compound is _______ $\times 10^{-1}\%$ (Nearest integer).

(Given : Molar mass of Ag is 108 and Br is $80\ \mathrm{g\ mol^{-1}}$)

Quantitative analysis of an organic compound (X) shows following % composition.

C : 14.5 %  Cl : 64.46%

H : 1.8 %

(Empirical formula mass of the compound (X) is ____ $\times 10^{-1}$

(Given molar mass in $\mathrm{g\ mol^{-1}}$ of C : 12, H : 1, O : 16, Cl : 35.5)

The purification method based on the following physical transformation is :

$$\underset{(X)}{\text{Solid}} \xrightarrow{\text{Heat}} \underset{(X)}{\text{Vapour}} \xrightarrow{\text{Cool}} \underset{(X)}{\text{Solid}}$$

Which of the following nitrogen containing compound does not give Lassaigne's test ?

The adsorbent used in adsorption chromatography is/are -

A. silica gel B. alumina C. quick lime D. magnesia

Choose the most appropriate answer from the options given below :

An organic compound has 42.1% carbon, 6.4% hydrogen and remainder is oxygen. If its molecular weight is 342, then its molecular formula is :

Using the given figure, the ratio of $R_f$ values of sample A and sample C is $x \times 10^{-2}$. Value of $x$ is ________.

[Figure: paper chromatography of samples (A, B, C) — base line at 0.0 cm, sample A spot at 5.0 cm, sample B spot at 6.5 cm, sample C spot at 10.0 cm, solvent front at 12.5 cm]

Which of the following statements are correct?

A. Glycerol is purified by vacuum distillation because it decomposes at its normal boiling point. B. Aniline can be purified by steam distillation as aniline is miscible in water. C. Ethanol can be separated from ethanol water mixture by azeotropic distillation because it forms azeotrope. D. An organic compound is pure, if mixed M.P. is remained same.

Choose the most appropriate answer from the options given below :

The correct statement among the following, for a "chromatography" purification method is :

In qualitative test for identification of presence of phosphorous, the compound is heated with an oxidising agent. Which is further treated with nitric acid and ammonium molybdate respectively. The yellow coloured precipitate obtained is :

Given below are two statements :

Statement (I) : Kjeldahl method is applicable to estimate nitrogen in pyridine.

Statement (II) : The nitrogen present in pyridine can easily be converted into ammonium sulphate in Kjeldahl method.

In the light of the above statements, choose the correct answer from the options given below :

Methods used for purification of organic compounds are based on :

[Figure: a TLC plate 10 cm tall with the baseline 1 cm from the bottom and the solvent front 1 cm from the top; spot B lies above spot A between the baseline and the solvent front]

In the given TLC, the distance of spot A & B are 5 cm & 7 cm, from the bottom of TLC plate, respectively.

$R_f$ value of B is $x \times 10^{-1}$ times more than A. The value of $x$ is ________.

In Kjeldahl's method for estimation of nitrogen, $\mathrm{CuSO_4}$ acts as :

Lassaigne's test is used for detection of :

Following Kjeldahl's method, 1g of organic compound released ammonia, that neutralised 10 mL of 2M $\mathrm{H_2SO_4}$. The percentage of nitrogen in the compound is ________ %.

Appearance of blood red colour, on treatment of the sodium fusion extract of an organic compound with $\mathrm{FeSO_4}$ in presence of concentrated $\mathrm{H_2SO_4}$ indicates the presence of element/s

The Lassiagne's extract is boiled with dil $\mathrm{HNO_3}$ before testing for halogens because,

On a thin layer chromatographic plate, an organic compound moved by 3.5 cm, while the solvent moved by 5 cm. The retardation factor of the organic compound is ________ $\times 10^{-1}$.

Which among the following purification methods is based on the principle of "Solubility" in two different solvents?

'Adsorption' principle is used for which of the following purification method?

Match List I with List II

	LIST I (Technique)		LIST II (Application)
A.	Distillation	I.	Separation of glycerol from spent-lye
B.	Fractional distillation	II.	Aniline - Water mixture
C.	Steam distillation	III.	Separation of crude oil fractions
D.	Distillation under reduced pressure	IV.	Chloroform - Aniline

Choose the correct answer from the options given below:

The fragrance of flowers is due to the presence of some steam volatile organic compounds called essential oils. These are generally insoluble in water at room temperature but are miscible with water vapour in vapour phase. A suitable method for the extraction of these oils from the flowers is -