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प्रश्न
Give scientific reasons:
The disaccharide sucrose gives negative Tollens test while the disaccharide maltose gives a positive Tollens test.
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उत्तर
- The structure of sucrose contains glycosidic linkage between C-1 of α-glucose and C-2 of β-fructose.
- Since the potential aldehyde and ketone groups of both the monosaccharide units are involved in the formation of the glycosidic bond (i.e., α, β-1,2- glycosidic bond), sucrose is a non-reducing sugar and gives negative Tollen’s test.
- The glycosidic bond in maltose is in between C-1 of one glucose ring and C-4 of the other (i.e., α -1,4-glycosidic linkage).
- The hemiacetal group at C-1 of the second ring is not involved in the glycosidic linkage. Hence, maltose is a reducing sugar and gives positive Tollen’s test.
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संबंधित प्रश्न
Give two evidences for presence of formyl group in glucose.
Draw a neat diagram for the following:
Haworth formula of glucopyranose.
Draw the structure of α-D glucopyranose.
Write chemical reaction for following conversions
glucose into glucoxime
Write chemical reaction for following conversions
glucose into gluconic acid
What is the action of the following reagents on glucose?
hydroxylamine
Define carbohydrates.
Write a commercial method for preparation of glucose.
Which of the following type of carbohydrates cannot be hydrolyzed?
Carbohydrates can contain which of the following chemical groups?
The reserve food material in animals is ____________.
Identify the sugar having the molecular formula C6H1206.
Fructose is the fruit sugar and chemically it is ketohexose but it has a ______ rather than a ______.
Identify the WRONG statement.
Which is the product obtained, when Br2 water reacts with glucose?
Match the Column I and Column II select the correct option.
| Column I | Column II | ||
| i. | Monosaccharides | a. | Stored energy in animals |
| ii. | Glycogen | b. | Polymer made from ß-glucose molecules |
| iii. | Cellulose | c. | Exoskeleton of arthropods |
| iv. | Chitin | d. | Building blocks of carbohydrates |
| e. | Plant hormone |
The number of asymmetric carbon atoms in the glucose molecule is ____________.
Which carbon atoms of α- D glucopyranose and β-D-fructofuranose respectively are linked together to form glycosidic linkage in sucrose?
Which among the following type of linkages is present in cellulose?
Prolonged heating of glucose with hot HI results in the formation of ____________.
Identify the INCORRECT statement regarding glucose.
Which of the following monosaccharide is a ketohexose?
Stachyose is ____________.
\[\ce{CH3 - CH2 - CH2 - Br ->[Na][dry ether] A ->[Cl2] B}\]
Identify the product B in the above reaction.
Which one of the following is NOT soluble in water?
Which of the following statements is NOT true for glyceraldehyde?
Glucose and gluconic acid treated with dilute nitric acid forms saccharic acid. What does this indicate?
Which of the following molecules reduces Fehling's solution?
What is the number of hydroxyl groups present in lactic acid?
Which of the following statement is NOT true about saccharic acid?
Which among the following sugars does not reduce Tollen's reagent?
Identify the number of oxygen atoms present in saccharic acid?
How many moles of acetic acid are obtained in the reaction when one mole glucose is treated with excess acetic anhydride?
What is the product obtained when Br2 water reacts with glucose?
Which one of the following rotates the plane polarized light towards left?
Assertion: A solution of sucrose in water is dextrorotatory. But on hydrolysis in the presence of little hydrochloric acid, it becomes levorotatory.
Reason: Sucrose hydrolysis gives equal amounts of glucose and fructose. As a result of this change in sign of rotation is observed.
Classify the following into monosaccharides, oligosaccharides and polysaccharides.
Starch
Lactose is made of ______.
A molecule of stachyose contains how many carbon atoms?
The two monosaccharides in a disaccharide are held together by ______ bonds.
Which carbon atoms of fructose are bonded together through oxygen forming fructofuranose?
Why carbohydrates are generally optically active.
Why carbohydrates are generally optically active?
The linkage present in Lactose is ______.
Write the Zwitter ion structure of alanine.
\[\ce{CH2OH - CO - (CHOH)4 - CH2 OH}\] is an example of ______.
\[\ce{CH2OH-CO-(CHOH)4-CH2OH}\] is an example of ______.
Why carbohydrates are generally optically active.
Two monosaccharides are held together by ______ bond.
Given below are two statements.
Statement I - Lactose on hydrolysis converts into glucose and galactose.
Statement II - Galactose also plays same role as glucose in respiration.
In light of the above statements, select the correct option given below.
What are the number of chiral carbon atoms and the number of formyl groups, respectively, present in ribose?
Which of the following is used to separate glucose and fructose from hydrolysate of sucrose?
