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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 scientific reasons:
Hydrolysis of sucrose is called inversion.
Give two evidences for presence of formyl group in glucose.
Glucose on oxidation with dilute nitric acid gives _______________
Write the name of the unit to which glucose unit is linked to from sucrose.
Write chemical reaction for following conversions
glucose into glucoxime
Classify the following carbohydrates into monosaccharide, disaccharide, oligosaccharide and polysaccharide:
glucose, cellulose, maltose, stachyose
Explain the classification of carbohydrates with examples.
What is the action of the following reagents on glucose?
hydrogen iodide
Define carbohydrates.
Draw the Haworth projection structure of the following.
α-D-(–)-Fructofuranose
Write a chemical reaction to convert glucose into glucose cyanohydrin.
Draw the structure of the pyran.
From the following identify an example of disaccharides.
Identify the substances having glycosidic bond and peptide bond, respectively in their structure:
Which of the following is the basic unit of carbohydrates?
Which of the following carbohydrate is sweet to taste?
Formation of lactose by conden ation results in the release of how many molecules of water?
Carbohydrates can contain which of the following chemical groups?
From the following identify the materials that are made up of cellulose.
i. Plant cell wall
ii. Exoskeleton of arthropods
iii. Paper from plant pulp
iv. Cotton fibre
Which is the product obtained, when Br2 water reacts with glucose?
Chitin is a/an ______.
The number of asymmetric carbon atoms in the glucose molecule is ____________.
Identify the CORRECT combination.
Which reagent among the following is used to confirm presence of aldehydic carbonyl group in glucose?
One mole of a carbohydrate on hydrolysis gives one mole of glucose and one mole of galactose. Identify the carbohydrate.
Which one of the following is generally applicable to polysaccharides?
Which one of the following carbohydrates is insoluble in water?
Which one of the following is NOT soluble in water?
Which of the following molecules reduces Fehling's solution?
Which following reagent is used to detect presence of five hydroxyl groups in a glucose molecule?
How many moles of fructose and galactose respectively are obtained on hydrolysis of 1 mole stachyose?
Identify the number of secondary carbon atoms in glucose.
What is the quantity of glucose obtained when 68.4 g of sucrose is hydrolyzed in laboratory under ideal condition?
(Molar mass of sucrose = 342 g mol−1)
Which among the following reagents is used for conversion of glucose to glucoxime?
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?
When one mole of lactose is hydrolysed, the hydrolysate contains ____________.
How many hydroxyl groups are present in Erythrulose?
Which among the following observations suggests that glucose also exists in cyclic form?
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.
Lactose
Match the Column I with Column II and choose the correct answer from options below:
| Column I | Column II |
| A. Purine | 1. Glycogen |
| B. Pyrimidine | 2. Cellulose |
| C. Structural polysaccharide | 3. Glucagon |
| D. Storage polysaccharide | 4. Adenine |
| 5. Cytosine |
Corn is immersed in boiling water. It is then cooled, and the solution becomes sweet. It is due to ______.
Identify the product obtained in the following conversion.
\[\ce{Glucose ->[(O)][Br2 water] Product}\]
The glycosidic linkage present in maltose is ______.
Why carbohydrates are generally optically active.
Why carbohydrates are generally optically active?
Describe the action of the following reagent on glucose:
Bromine water
Write Fischer projection formulae for glucose.
Explain the hydrolysis of sucrose.
\[\ce{CH2OH - CO - (CHOH)4 - CH2OH}\] is an example of ______.
