Tag: chemistry

Questions Related to chemistry

Which of the following does not reduce Benedict's solution?

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. Sucrose

  2. Aldehyde

  3. Glucose

  4. Fructose

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Correct Option: A
Explanation:
 Sucrose.. 
Because Sucrose (table sugar) contains two sugars (fructose and glucose) joined by their glycosidic bond in such a way as to prevent the glucose isomerizing to aldehyde, or the fructose to alpha-hydroxy-ketone form. Sucrose is thus a non-reducing sugar which does not react with Benedict's reagent.

In plant glycolipids, the sugar is normally.

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. oil

  2. wax

  3. glycolipid

  4. phospholipid

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Correct Option: C
Explanation:

Glycolipids yeild fatty acids, glycerol and carbohydrates on hydrolysis. Monogalactosyldiglycerides are glycolipids which are commonly found in plant leaves and algae. They contain a high proportion of poly unsaturated fatty acids and appear to play a role in photosynthesis.

Which of the following is/are correctly matched?

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. D-Glucose & L-Galactose -Epimer

  2. Fructose & Mannose - Fundamental isomers

  3. D-Glucose & D-Mannose & Diatereomers

  4. $\alpha$-D-Glucopyranose & $\beta-D-Glucopytranose-Anomers

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Correct Option: A

Carbohydrates may be:

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. sugars

  2. starch

  3. polyhydroxy aldehyde/ketones

  4. compounds that can be hydrolyzed to sugar

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Correct Option: A,B,C,D
Explanation:

Carbohydrates are primarily produced by plants and form a very large group of naturally occurring organic compounds. Some common examples are cane sugar, glucose, starch, etc.
The carbohydrates may be defined as optically active polyhydroxy aldehydes or ketones or the compounds which produce such units on hydrolysis.

Which among the following is the main constituent of Biogas?

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. Methane

  2. Propane

  3. Butane

  4. Ethane

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Correct Option: A

For the reduction of glucose to n-hexane, the reagent used is:

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. $HBr$

  2. $HCl$

  3. $HF$

  4. $HI$

Show answer
Correct Option: D
Explanation:

For the reduction of glucose to n-hexane, the reagent used is $HI$.
Glucose is heated with $HI$, n-hexane is obtained which suggests that all the six carbons are linked in a straight chain.

Which of the following is true regarding monosaccharides?

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. Always have six carbon atoms

  2. Always have five carbon atoms

  3. Always have four carbon atoms

  4. May contain 3 to 7 carbon atoms

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Correct Option: D
Explanation:

Monosaccharides may contain 3 to 7 carbon atoms. They have chemical formula $(CH _2O) _{n}$, where conventionally $n=3$. Monosaccharides can be classified by the number of carbon atoms they contain: diose(2), triose(3), tetrose(4), pentose(5), hexose(6), heptose(7) and so on.

Raffinose on hydrolysis forms_________

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. Glucose

  2. Fructose

  3. Galactose

  4. All of these

Show answer
Correct Option: D
Explanation:

Raffinose is a trisaccharide and consists of 1 unit of glucose, fructose and galactose each. 


So on hydrolysis, it breaks into glucose, fructose and galactose. 

So, D is correct.

Which of the following is synthetic sweetener?

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. Saccharin

  2. Aspartame

  3. Dulcin

  4. All of  the above

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Correct Option: D
Explanation:

Saccharin, aspartame, dulcin all are synthetic sweetener. They have a sugar-like taste but with less food energy.

Artificial sweeteners are used in one of two ways. They may be used directly in commercially processed foods, or they are mixed with one or more starch-based sweeteners before sale to consumers.


$\therefore$ Option D is the correct answer.

Which of the following is incorrect?

carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

  1. Fructose is reducing sugar

  2. Cellulose has $\beta$-D Glucose units

  3. DNA has D-ribose

  4. Amylopectin is insoluble in water

Show answer
Correct Option: C
Explanation:

Fructose is reducing sugar.
 
Cellulose is a polysaccharide composed of a linear chain of  $\beta $ 1,4 linked d glucose unit.with a degree of polymerization ranged from several hundreds to over ten thousands.

Amylopectin is a highly branched polymer of glucose found in plants. It is one of the two components of starch, the other being amylose.

As the name suggest DNA is deoxyribonucleic acid hence it has deoxyribose sugar not ribose sugar.