carbohydrates-chemistry-jee-main-questions

Q 11 :

Given below are two statements: [2025]

Statement I: Fructose does not contain an aldehydic group but still reduces Tollen’s reagent.

Statement II: In the presence of base, fructose undergoes rearrangement to give glucose.

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

Statement I is false but Statement II is true
Both Statement I and Statement II are true
Both Statement I and Statement II are false
Statement I is true but Statement II is false

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(2)

Q 12 :

Given below are two statements: [2025]

Statement I: D-glucose pentacetate reacts with 2,4-dinitrophenylhydrazine.

Statement II: Starch, on heating with concentrated sulfuric acid at 100°C and 2–3 atmosphere pressure produces glucose.

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

Both Statement I and Statement II are false
Both Statement I and Statement II are true
Statement I is true but Statement II is false
Statement I is false but Statement II is true

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(4)

The pentaacetate of glucose does not react with 2,4-dinitrophenylhydrazine indicating the absence of free —CHO group.

Starch is a polymer of $α$ -D-glucose, hence upon hydrolysis of starch, glucose is produced.

Q 13 :

Match List I with List II [2025]

List I List II

(Saccharides) (Glycosidic-linkages found)

(A) Sucrose (I) $α$ 1 – 4

(B) Maltose (II) $α$ 1 – 4 and $α$ 1 – 6

(C) Lactose (III) $α$ 1 – $β$ 2

(D) Amylopectin (IV) $β$ 1 – 4

Choose the correct answer from the options given below:

(A)-(II), (B)-(IV), (C)-(III), (D)-(I)
(A)-(I), (B)-(II), (C)-(III), (D)-(IV)
(A)-(IV), (B)-(II), (C)-(I), (D)-(III)
(A)-(III), (B)-(I), (C)-(IV), (D)-(II)

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(4)

Sucrose: Its structure consists of a glycosidic linkage between $C_{1}$ of $α$ -D-glucose and $C_{2}$ of $β$ -D-fructose.

Maltose: It is composed of two $α$ -D-glucose units in which $C_{1}$ of one glucose (I) is linked to $C_{4}$ of another glucose unit (II).

Lactose: It is composed of $β$ -D-galactose and $β$ -D-glucose. The linkage is between $C_{1}$ of galactose and $C_{4}$ of glucose.

Amylopectin: It is a branched chain polymer of $α$ -D-glucose units in which chain is formed by $C_{1} - C_{4}$ glycosidic linkage whereas branching occurs by $C_{1} - C_{6}$ glycosidic linkage.

Q 14 :

Identify correct conversion during acidic hydrolysis from the following:

(A) Starch gives galactose.
(B) Cane sugar gives equal amount of glucose and fructose.
(C) Milk sugar gives glucose and galactose.
(D) Amylopectin gives glucose and fructose.
(E) Amylose gives only glucose.

Choose the correct answer from the options given below: [2025]

(B), (C) and (E) only
(A), (B) and (C) only
(C), (D) and (E) only
(B), (C) and (D) only

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(1)

(A)(D)(E) Starch – Starch is the main storage polysaccharide of plants. Amylose and Amylopectin are two components of starch. Amylose is a long unbranched chain with 200–1000 $α$ -D-(+)-glucose units held together by $C_{1} - C_{4}$ glycosidic linkage. Amylopectin is a branched chain polymer of $α$ -D-glucose units in which chain is formed by $C_{1} - C_{4}$ glycosidic linkage whereas branching occurs by $C_{1} - C_{6}$ glycosidic linkage. Hence hydrolysis of starch/amylose/amylopectin gives $α$ -D-(+)-glucose.

(B) Sucrose (cane sugar) consists of a glycosidic linkage between $C_{1}$ of $α$ -D-glucose and $C_{2}$ of $β$ -D-fructose. Hence on hydrolysis it gives equal amount of glucose and fructose.

(C) Lactose (milk sugar): It is composed of $β$ -D-galactose and $β$ -D-glucose. The linkage is between $C_{1}$ of galactose and $C_{4}$ of glucose. Hence on hydrolysis it gives galactose and glucose.

Q 15 :

Match List I with List II [2025]

List I List II

(Carbohydrate) (Linkage Source)

(A) Amylose (I) $β - C_{1} - C_{4}$ , plant

(B) Cellulose (II) $α - C_{1} - C_{4}$ , animal

(C) Glycogen (III) $α - C_{1} - C_{4} . α - C_{1} - C_{6}$ , plant

(D) Amylopectin (IV) $α - C_{1} - C_{4}$ , plant

Choose the correct answer from the options given below:

(A)-(II), (B)-(III), (C)-(I), (D)-(IV)
(A)-(IV), (B)-(I), (C)-(III), (D)-(II)
(A)-(III), (B)-(II), (C)-(I), (D)-(IV)
(A)-(IV), (B)-(I), (C)-(II), (D)-(III)

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(4)

(A) (D) Starch is the main storage polysaccharide of plants. Amylose and Amylopectin are two components of starch. Amylose is a long unbranched chain with 200–1000 $α$ -D-(+)-glucose units held together by $C_{1} - C_{4}$ glycosidic linkage. Amylopectin is insoluble in water and constitutes about 80–85% of starch. It is a branched chain polymer of $α$ -D-glucose units in which chain is formed by $C_{1} - C_{4}$ glycosidic linkage whereas branching occurs by $C_{1} - C_{6}$ glycosidic linkage.

(B) Cellulose is a predominant constituent of the cell wall of plant cells. Cellulose is a straight chain polysaccharide composed only of $β$ -D-glucose units which are joined by glycosidic linkage between $C_{1}$ of one glucose unit and $C_{4}$ of the next glucose unit.

(C) The carbohydrates are stored in the animal body as glycogen. It is also known as animal starch because its structure is similar to amylopectin and is rather more highly branched.

Q 16 :

Match items of Row I with those of Row II.

Row I :

[IMAGE 468]

Row II:
(i) $α - D$ -(–)-Fructofuranose
(ii) $β - D$ -(–)-Fructofuranose
(iii) $α - D$ -(–)-Glucopyranose
(iv) $β - D$ -(–)-Glucopyranose

Correct match is [2023]

A → iii, B → iv, C → ii, D → i
A → iv, B → iii, C → i, D → ii
A → iii, B → iv, C → i, D → ii
A → i, B → ii, C → iii, D → iv

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(3)

[IMAGE 469]

Q 17 :

The correct representation in six-membered pyranose form for the following sugar [X] is [2023]

[IMAGE 470]

[IMAGE 471]
[IMAGE 472]
[IMAGE 473]
[IMAGE 474]

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(1)

Pyranose form has a 6 membered cycle, similar to pyran [IMAGE 475]

Q 18 :

L-isomer of tetrose X $(C_{4} H_{8} O_{4})$ gives positive Schiff’s test and has two chiral carbons. On acetylation, 'X' yields triacetate. ‘X’ also undergoes the following reactions.

$' A' \overset{{HNO}_{3}}{\leftarrow}$ $' X' \overset{{NaBH}_{4}}{\leftarrow}$ $\underset{chiral compound}{' B'}$

‘X’ is _______ [2023]

[IMAGE 476]
[IMAGE 477]
[IMAGE 478]
[IMAGE 479]

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(4)

[IMAGE 480]

Q 19 :

$D-(+)-Glyceraldehyde$ $\to_{\begin{matrix} {ii)H}_{2} O / H^{+} \\ {iii)HNO}_{3} \end{matrix}}^{i) HCN}$

The products formed in the above reaction are [2023]

One optically active and one meso product
One optically inactive and one meso product
Two optically active products
Two optically inactive products

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(1)

[IMAGE 481]

Q 20 :

[IMAGE 482]

‘A’ formed in the above reaction is [2023]

[IMAGE 483]
[IMAGE 484]
[IMAGE 485]
[IMAGE 486]

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(1)

[IMAGE 487]

Topic Question Set

Q 16 :

Match items of Row I with those of Row II.

Row I :

[IMAGE 468]

Row II:
(i) $α - D$ -(–)-Fructofuranose
(ii) $β - D$ -(–)-Fructofuranose
(iii) $α - D$ -(–)-Glucopyranose
(iv) $β - D$ -(–)-Glucopyranose

Correct match is [2023]

Q 17 :

The correct representation in six-membered pyranose form for the following sugar [X] is [2023]

[IMAGE 470]

Q 19 :

$D-(+)-Glyceraldehyde$ $\to_{\begin{matrix} {ii)H}_{2} O / H^{+} \\ {iii)HNO}_{3} \end{matrix}}^{i) HCN}$

The products formed in the above reaction are [2023]

Q 20 :

[IMAGE 482]

‘A’ formed in the above reaction is [2023]

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	List I		List II
	(Saccharides)		(Glycosidic-linkages found)
(A)	Sucrose	(I)	$α$ 1 – 4
(B)	Maltose	(II)	$α$ 1 – 4 and $α$ 1 – 6
(C)	Lactose	(III)	$α$ 1 – $β$ 2
(D)	Amylopectin	(IV)	$β$ 1 – 4

	List I		List II
	(Carbohydrate)		(Linkage Source)
(A)	Amylose	(I)	$β - C_{1} - C_{4}$ , plant
(B)	Cellulose	(II)	$α - C_{1} - C_{4}$ , animal
(C)	Glycogen	(III)	$α - C_{1} - C_{4} . α - C_{1} - C_{6}$ , plant
(D)	Amylopectin	(IV)	$α - C_{1} - C_{4}$ , plant

Topic Question Set

Q 20 : [IMAGE 482] ‘A’ formed in the above reaction is [2023] .question-row { display: flex; align-items: flex-start; gap: 8px; } .q-no { font-size: 17px; white-space: nowrap; margin-left: -15px; } .q-text { font-size: 18px; flex: 1; } .q-no, .q-text p { line-height: 30px; }

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Q 20 :

[IMAGE 482]

‘A’ formed in the above reaction is [2023]