Tag: introduction to carbohydrates

Questions Related to introduction to carbohydrates

Which of the following compounds will not undergo decomposition on passing electricity through aqueous solution?

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. Sugar

  2. Sodium chloride

  3. Sodium bromide

  4. Sodium acetate

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Correct Option: A
Explanation:

Sodium chloride, sodium bromide, and sodium acetate are all ionic compounds and hence, they dissociate into their respective ions in an aqueous solution. On the contrary, sugar is a covalent compound and hence does not dissociate into ions

The two functional groups present in a typical carbohydrate are :

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. $-CHO$ and $-COOH$

  2. $-CO$ and $-OH$

  3. $-OH$ and $-CHO$

  4. $-OH$ and $-COOH$

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Correct Option: B
Explanation:

Carbohydrates are polyhydroxy aldehydes or polyhydroxy ketones OR compounds which give aldehydic as well as ketonic groups on hydrolysis. Therefore the major functional groups are (carbonyl) Aldehyde, Ketone, and hydroxy groups. 

Out of $1$M glucose and $2$M glucose. 2M glucose has  a higher boiling point.

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. True

  2. False

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Correct Option: A
Explanation:

2 M glucose has a higher boiling point than 1 M of glucose.

Since on increasing the no of moles the molality also increases which is directly proportional to an elevation in boiling point.
Thus, the boiling point of the 2M of glucose will be greater than 1M glucose.

Which among the following is not the example of carbohydrate ?

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. Glucose 

  2. fractose

  3. Maltose

  4. Nylon

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Correct Option: D
Explanation:

$\rightarrow$ Carbohydrates are important source of instant energy in our body system.
$\rightarrow$ Honey has been used as instant source of enrgy in ayurvedic medicines.
$\rightarrow$ Carbohydrates are used as storage starch in plants and glycogen
$\rightarrow$ carbohydrates are also used in textile industry.

So, the correct answer is NYLON (It is a synthetic polymer)

For 'invert sugar', the correct statement(s) is (are)
(Given : specific rotations of (+) -sucrose, (+) -maltose, L-(-)-glucose and L-(+)-fructose in aqueous solution are $+66^0, +140^0, -52^0$ and $92^0$, respectively)

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. 'invert sugar' is prepared by acid catalyzed hydrolysis of maltose

  2. 'invert sugar' is an eqimolar mixture of D-(+)-glucose and D-(-)-fructose

  3. specific rotation of 'invert sugar' is $-20^0$

  4. on reaction with $Br _2$ water, 'invert sugar' forms saccharic acid as one of the products

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Correct Option: A
Explanation:

Invert sugar is a sucrose, partially or totally cleaved into fructose and glucose. Sucrose is converted into  invert sugar by chemical reaction called hydrolysis by heating a mixture or solution of table sugar.

Also, breakdown of sucrose may happen in a reaction catalyzed by enzymes such as sucrose, invertase etc or by acid catalyzed hydrolysis of maltose.

One mole of each of glucose and fructose require $x$ and $y$ moles of periodic acid respectively, for oxidation. Hence, $x/y$ is

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. $1/1$

  2. $2/1$

  3. $5/4$

  4. $9/4$

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Correct Option: A

Molisch test is answered by

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. All carbohydrates

  2. Sucrose

  3. Fructose
  4. Glucose
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Correct Option: A
Explanation:

Molisch test is a test for carbohydrate or compounds which can be dehydrated to furfural or furfural derivatives in the presence of the concentrated sulphuric acid .

In fructose and glucose the possible optical isomers are:

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. 12, 12

  2. 8, 16

  3. 16, 8

  4. 4, 12

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Correct Option: B
Explanation:
Fructose contains three chiral carbon atom and glucose contain 4 chiral carbon atoms.
The Number of possible Optical isomers for Fructose are ${2}^{3} = 8$
The Number of possible Optical isomers for Glucose are ${2}^{4} = 16$
8, 16 is the Answer

The $\alpha$- D glucose and $\beta$- D glucose differ from each other due to difference in carbon atom with respect to its

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. Number of $OH$ groups

  2. Size of hemiacetal ring

  3. Conformation

  4. Configuration

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Correct Option: D

What is the nature of glucose-glucose linkage in starch that males its so susceptible to acid hydrolysis?

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. Starch is hemiacetal

  2. Starch is acetal

  3. Starch is polymer

  4. Starch contain only few molecules of glucose

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Correct Option: B