Test: Carbohydrates


20 Questions MCQ Test Chemistry Class 12 | Test: Carbohydrates


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This mock test of Test: Carbohydrates for Class 12 helps you for every Class 12 entrance exam. This contains 20 Multiple Choice Questions for Class 12 Test: Carbohydrates (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Carbohydrates quiz give you a good mix of easy questions and tough questions. Class 12 students definitely take this Test: Carbohydrates exercise for a better result in the exam. You can find other Test: Carbohydrates extra questions, long questions & short questions for Class 12 on EduRev as well by searching above.
QUESTION: 1

On hydrolysis maltose gives:

Solution:

Maltose can be produced from starch by hydrolysis in the presence of the enzyme diastase. It can be broken down into two glucose molecules by hydrolysis. In living organisms, the enzyme maltase can achieve this very rapidly. In the laboratory, heating with a strong acid for several minutes will produce the same result.

QUESTION: 2

The commonest disaccharide have the molecular formula:​

Solution:

Sucrose or cane sugar is the commonest of the disaccharides. It has the molecular formula C12H22O11. It does not form a phenylhydrazone or exhibit carbonyl properties. On hydrolysis with dilute acids, it yields one molecule of D-(+)-glucose and one molecule of D-(—)-fructose. It is not a reducing sugar. 

QUESTION: 3

Glucose and fructose are:

Solution:

Glucose and fructose are functional isomers of each other Because they have same molecular formula that is C6H12O6 But different functional group in their chemical formula. Glucose has aldehyde group while fructose has ketone as functional group.

QUESTION: 4

Which of the following carbohydrates is called milk sugar?

Solution:

Lactose: The sugar found naturally in milk, it is a disaccharide composed of one galactose unit and one glucose unit; sometimes called milk sugar.

QUESTION: 5

The following is a reaction of glucose with Fehling’s reagent. What will happen in the reaction?

Solution:

Because it is the chemical property of aliphatic aldehyde to give red precipitate with fehling solution.

RCHO + 2 CuO -----------> Cu2O. + RCOOH

Fehling reagents is aq. alkaline CuSO4 solution along with Rochelle salt Na-K tartrate.
And glucose molecule consists of aldehydic group at first position and hence it is also a aldehyde and thus give this characteristic test.

QUESTION: 6

The oxide linkage formed by the loss of a water molecule when two monosaccharides are joined together through oxygen atom is called:

Solution:

Fructose is an important ketohexose. It is obtained along with glucose by the hydrolysis of disaccharide, sucrose. The two monosaccharides are joined together by an oxide linkage formed by the loss of a water molecule. Such a linkage between two monosaccharide units through oxygen atom is called Glycosidic Linkage.

QUESTION: 7

Glucose + Tollen’s reagent → Silver mirror. The process shows:

Solution:
QUESTION: 8

Identify the following compound:

 

Solution:
QUESTION: 9

The compound which gives red colour with Fehling’s solution?

Solution:

Fehling's solution to make difference between carbohydrate and ketone functional grp and also used for differentiate reducing and non reducing sugar and as u know glucose is a reducing sugar so it will give red colour with fehling's solution (all monosachharides are reducing sugar).

QUESTION: 10

In polysaccharides, the linkage connecting monosaccharides is called:

Solution:
  • Disaccharides on hydrolysis with dilute acids or enzymes yield two molecules of either the same or different monosaccharides.
  • The two monosaccharides are joined together by an oxide linkage formed by the loss of a water molecule. Such a linkage between two monosaccharide units through oxygen atom is called glycosidic linkage.
QUESTION: 11

Glucose reacts with acetic anhydride to form:

Solution:

It forms glucose pentaacetate. The acetic anhydride esterifies with all the alcohol groups on the glucose ring.

QUESTION: 12

What does the following reaction of glucose with HI elucidates about the structure of glucose?

Solution:

Reaction of glucose with HI forms hexane. This reaction shows the presence of six carbons linked linearly in glucose.

QUESTION: 13

The Molisch test is a chemical test that determines the presence of:

Solution:

The Molisch test uses concentrated sulphuric acid as the dehydrating acid. This acid dehydrates all carbohydrates, so the test is used to distinguish between carbohydrates and non-carbohydrates. 

QUESTION: 14

What does the following reaction shows about the structure of glucose?

Solution:
QUESTION: 15

Which among the following is a non-reducing sugar?

Solution:

Non-reducing sugars do not have an OH group attached to the anomeric carbon so they cannot reduce other compounds. All monosaccharides such as glucose are reducing sugars. A disaccharide can be a reducing sugar or a non-reducing sugar. Maltose and lactose are reducing sugars, while sucrose is a non-reducing sugar.

QUESTION: 16

Which of the following carbohydrates is called an invert sugar?

Solution:

It is called invert sugar because the angle of the specific rotation of the plain polarized light changes from a positive to a negative value due to the presence of the optical isomers of the mixture of glucose and fructosesugars.

QUESTION: 17

What is the relation between the following pairs of monosaccharides?

Solution:

The pairs of optical isomers which differ in configuration around any other C atom other than Catom are called epimers. D-glucose and D-mannose are C2 epimers.

 

QUESTION: 18

Hydrolysis of sucrose is called:

Solution:

 

Hydrolysis of sucrose to give glucose and fructose is called inversion. hydrolysis of sucrose brings about a change in the sign of rotation, from dextro (+) to laevo (–) and the product is named as invert sugar.

QUESTION: 19

Which of the following carbohydrate is an example of an oligosaccharide?

Solution:

Lactose intolerance is the inability to break down a type of natural sugar called lactose. Lactose is commonly found in dairy products, such as milk and yogurt. A person becomes lactose intolerant when his or her small intestine stops making enough of the enzyme lactase to digest and break down the lactose.

QUESTION: 20

Sucrose is a non-reducing sugar because:​

Solution:

Sucrose is a non-reducing sugar because the two monosaccharide units are held together by a glycosidic linkage between C1 of α-glucose and C2 of β-fructose. Since the reducing groups of glucose and fructose are involved in glycosidic bond formation, sucrose is a non-reducing sugar.