CBSE > Class 12 > Chemistry | CBSE Board | Homework Help

image164.png Below are three representations of the open chain form of D-glucose: in the conventional Fischer projection (A), in the “line structure” variation of the Fischer projection in which carbons and hydrogens are not shown (B), and finally in the 'zigzag' style (C) that is preferred by organic chemists. image166.png Care must be taken when ‘translating’ Fischer projection structures into' zigzag' format – it is easy to get the stereochemistry wrong. Probably the best way to make a translation is to simply assign R/S configurations to each stereocenter, and proceed from there. When deciding whether a stereocenter in a Fischer projection is R or S, realize that the hydrogen, in a horizontal bond, is pointing towards you – therefore, a counterclockwise circle means R, and a clockwise circle means S (the opposite of when the hydrogen is pointing away from you). image168.png Fischer projections are useful when looking at many different diastereomeric sugar structures, because the eye can quickly pick out stereochemical differences according to whether a hydroxyl group is on the left or right side of the structure. image170.png Exercise 3.24: Draw 'zigzag' structures (using the solid/dash wedge convention to show stereochemistry) for the four sugars in the figure above. Label all stereocenters R or S. To make it easy to check your answers, draw your structures using the framework below. Solutions to exercises While Fischer projections are used for sugars in their open-chain form, Haworth projections are often used to depict sugars in their cyclic forms. The beta diastereomer of the cyclic form of glucose is shown below in three different depictions, with the Haworth projection in the middle.

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Amol Gùpta 6 years, 5 months ago

Haa h to pr samajhne me prblm ho rhi h

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Ɽøⱨł₮ ₲Ʉ₱₮₳ 6 years, 5 months ago

Book me diya Hoga

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Amol Gùpta 6 years, 5 months ago

Koi baat naa tumne hlp to ki

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Amol Gùpta 6 years, 5 months ago

To ab mai kya kru

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Ɽøⱨł₮ ₲Ʉ₱₮₳ 6 years, 5 months ago

Show Karana impossible h

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Amol Gùpta 6 years, 5 months ago

Bhai ye to book se study kr liya structure me prblm ho rhi h

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Ɽøⱨł₮ ₲Ʉ₱₮₳ 6 years, 5 months ago

A Haworth projection is a common way of writing a structural formula to represent the cyclic structure of monosaccharides with a simple three-dimensional perspective. Organic chemistry and especially biochemistry are the areas of chemistry that use the Haworth projection the most.

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Kya is baar practical dusre centre par hoga

Posted by Abhay Yadav 6 years, 5 months ago

CBSE > Class 12 > Chemistry

3 answers

K@Łp@N@ $Øđh!?? 6 years, 5 months ago

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Priya Upadhyay 6 years, 5 months ago

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Priya Dharshini 6 years, 5 months ago

Yes.... practical are going to be held in different schools..

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Isotonic solution have same Solute Density Elevation in bp Depression ib fp

Posted by Priti Singh 6 years, 5 months ago

CBSE > Class 12 > Chemistry

0 answers

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Calculate the EMF of following cell at 298 Kelvin . Mg|Mg2+(0.1M)||cu2+(1×10^-3)|cu E°=2.71 V

Posted by Smr Ladhar 6 years, 5 months ago

CBSE > Class 12 > Chemistry

0 answers

ANSWER

The following curve is obtained when molar conductivity is plotted against square root of concentration C 1÷2 ( x-axis )for two electrolytes A and B. a.)what can you say about nature of two electrolytes A and B. b.)how do you account for increase in molar conductivity for electrolytes A and B on dilution

Posted by Smr Ladhar 6 years, 5 months ago

CBSE > Class 12 > Chemistry

0 answers

ANSWER

Why is sulphuric acid not used during the reaction of alcohols with KI??

Posted by Dàñïyã Ãrshãd? 6 years, 5 months ago

CBSE > Class 12 > Chemistry

2 answers

Dàñïyã Ãrshãd? 6 years, 5 months ago

Thnku @Aman Yadav

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Aman Yadav 6 years, 5 months ago

Because in presence of h2so4, kI will react with h2so4 to form hydrogen iodide,iodoalkanes will not form

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Give an example of a metal oxide which is highly ferromagnetic substance

Posted by Ankika Halder 6 years, 5 months ago

CBSE > Class 12 > Chemistry

0 answers

ANSWER

Will be the logarithm values given in board exams?

Posted by Rudra Singh 6 years, 5 months ago

CBSE > Class 12 > Chemistry

5 answers

Tanvi Toor 6 years, 5 months ago

Yes they will be given

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Rakesh Meel 6 years, 5 months ago

Yes they will be given but some normal value would not be given

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Krishan Singh 6 years, 5 months ago

Maybe not

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Rudra Singh 6 years, 5 months ago

Upto 10 also?

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Priya Dharshini 6 years, 5 months ago

Yes... they will provide...

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What is the value of vant hoff factor when acetic acid dissolve in water

Posted by Prabhjot Prabhjot 6 years, 5 months ago

CBSE > Class 12 > Chemistry

1 answers

Avantika Tayal 6 years, 5 months ago

Since acetic acid is a week electrolyte it undergoes association.so vant if factor is 0.5

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ANSWER

Which Force act of methanol and acetone

Posted by Kamlesh Kumar 6 years, 5 months ago

CBSE > Class 12 > Chemistry

5 answers

Priya Dharshini 6 years, 5 months ago

Methanol and acetone, both are polar and so the intermolecular force of attraction will be dipole-dipole interaction.

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Kamlesh Kumar 6 years, 5 months ago

Which was correct

1Thank You

Kamlesh Kumar 6 years, 5 months ago

Explain that question with answer

1Thank You

Kamlesh Kumar 6 years, 5 months ago

Dipole dipole interactions

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Students Club 6 years, 5 months ago

Hydrogen bond

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which is the better redusing agent at 983 k carbon or co and why?

Posted by Manish Kumar 6 years, 5 months ago

CBSE > Class 12 > Chemistry

1 answers

S.... ????☺ 6 years, 5 months ago

I think lithium aluminum hydride is strong redusing agent in Carbonyl compounds

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ANSWER

Why is the prepration of phenol INDUSTRIALLY is prefered from cumene although Dow's process is also a good method to prepare phenol?

Posted by Vishakha Dixit 6 years, 5 months ago

CBSE > Class 12 > Chemistry

2 answers

Vishakha Dixit 6 years, 5 months ago

What

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S.... ????☺ 6 years, 5 months ago

Yes

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ANSWER

LiAlH4 name of this

Posted by Ɽøⱨł₮ ₲Ʉ₱₮₳ 6 years, 5 months ago

CBSE > Class 12 > Chemistry

6 answers

Rajat Barwar 6 years, 5 months ago

Lithium aluminium hydride, it is a strong reducing agent which convert aldehyde,ketone,carboxylic acid, ester etc. into alcohol. Hope it may help you.

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Vishakha Dixit 6 years, 5 months ago

Welcome?

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Ɽøⱨł₮ ₲Ʉ₱₮₳ 6 years, 5 months ago

Tnx Vishakha

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Ɽøⱨł₮ ₲Ʉ₱₮₳ 6 years, 5 months ago

Mtlab

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Vishakha Dixit 6 years, 5 months ago

Lithium aluminium hydride

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Harsh Mishra 6 years, 5 months ago

Hogi tumhari koi Alien Language......

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How can we differentiate b/w homopolymer and copolymer ?? Please reply fast

Posted by Amol Gùpta 6 years, 5 months ago

CBSE > Class 12 > Chemistry

5 answers

Ɽøⱨł₮ ₲Ʉ₱₮₳ 6 years, 5 months ago

Welcome îshika

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Ďãřşháñăã Yadav ? ? ? 6 years, 5 months ago

wello ?

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Amol Gùpta 6 years, 5 months ago

Thanks rohit and darshu

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Ďãřşháñăã Yadav ? ? ? 6 years, 5 months ago

Homopolymers :- the polymers are formed by the polymerization of single monomeric species e. g. formation of polythene from ethene. Copolymer :- these polymer are formed by the polymerization of two different monomers e. g, formation of buna-s from styrene and bita-1,3-diene. some common addition polymers are polythene, polystyrene, treflon, buna-s, pvc etc.

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Ɽøⱨł₮ ₲Ʉ₱₮₳ 6 years, 5 months ago

Homopolymers consist of single species of repeating units. Copolymers consist of two or more type of repeating units. Amount of Monomer Species Homopolymers have a single type of monomer. Copolymers have two or more types of monomers. Chemical Structure Homopolymers usually have a simple structure. Copolymers have a complex structure. Polymerization Process Homopolymers are formed through addition polymerization. Copolymers are formed through condensation polymerization. Examples Homopolymers include PVC, polyethylene, polypropylene, polystyrene, polytetrafluoroethylene, and poly(methyl methacrylate). Copolymers include poly (vinyl acetate), poly (ethylene oxide), poly(ethylene terephthalate) and poly(hexamethylene sebaacamide).

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ANSWER

Why is chloroform stored in dark coloured bottle

Posted by Ɽøⱨł₮ ₲Ʉ₱₮₳ 6 years, 5 months ago

CBSE > Class 12 > Chemistry

7 answers

Ɽøⱨł₮ ₲Ʉ₱₮₳ 6 years, 5 months ago

Jahnavi aap kis school ho

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Jahnavi Joshi 6 years, 5 months ago

Welcome

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Ɽøⱨł₮ ₲Ʉ₱₮₳ 6 years, 5 months ago

Thanks jahnavi

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Jahnavi Joshi 6 years, 5 months ago

Chloroform stored in dark coloured bottles because on oxidation in air and sunlight it will give phosgene gas which is highly poisonous

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Ďãřşháñăã Yadav ? ? ? 6 years, 5 months ago

welcome ✌️

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Ɽøⱨł₮ ₲Ʉ₱₮₳ 6 years, 5 months ago

Thanks

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Ďãřşháñăã Yadav ? ? ? 6 years, 5 months ago

becoz in presence of light or we can say sunlight they converted into poisonous chemical.

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ANSWER

How to convert aniline to clorobenzene

Posted by Sukhmanpreet Kaur 6 years, 5 months ago

CBSE > Class 12 > Chemistry

1 answers

Priya Dharshini 6 years, 5 months ago

Sandmayers reaction.... aniline to bdc then cucl and hcl u will get chlorobenzene..

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ANSWER

aniline does not undergo friedel crafts rxn justify.

Posted by Řøhăň Řąjpůť ✌️✊ 6 years, 5 months ago

CBSE > Class 12 > Chemistry

4 answers

Sia ? 6 years, 5 months ago

Aniline does not undergo Friedel craft's reactions because the reagent AlCl₃ (the Lewis acid which is used as a catalyst in friedel crafts reaction), being electron deficient acts as a Lewis base.

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Řøhăň Řąjpůť ✌️✊ 6 years, 5 months ago

thx both of u

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Ďãřşháñăã Yadav ? ? ? 6 years, 5 months ago

*strong deactivating

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Ďãřşháñăã Yadav ? ? ? 6 years, 5 months ago

aniline forms salt with friedel crafts catalyst AlCl3. in this salt N atom acquires +ve charge nd acts as string deactivated grp. hence the reactivity is ⬇️sed

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ANSWER

What will be formed when con.H2SO4 is added with charcoal?

Posted by Tarun Kumar 6 years, 5 months ago

CBSE > Class 12 > Chemistry

0 answers

ANSWER

An inorganic salt when heated with concn H2SO4 evolves a colourless pungent smelling bt cocn H2SO4and MnO2 evolves a coloured pungent smelling gas which bleaches moist litmus paper.The colour ed gas is

Posted by Tarun Kumar 6 years, 5 months ago

CBSE > Class 12 > Chemistry

0 answers

ANSWER

Hoffman bromide reaction is also called hoffman degradation reaction why

Posted by Suraj Kumar 6 years, 5 months ago

CBSE > Class 12 > Chemistry

1 answers

Sohan .G 6 years, 5 months ago

Hoffman bromide reaction is called an Hoffman bromide degradation reaction because in the reaction a C=O group is reduced O || R-C-NH2+Br2+4NaOH ->R-NH2+Na2CO3+2NaBr+2H2O

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p atom at corner nd Q atom is alternate.Derive the furmula?

Posted by R.K Gupta 6 years, 5 months ago

CBSE > Class 12 > Chemistry

0 answers

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Is all closed chain compound aromatic??? Gibe example

Posted by Soumya Kumari 6 years, 5 months ago

CBSE > Class 12 > Chemistry

2 answers

Rajat Barwar 6 years, 5 months ago

No,there are many examples, Cyclohexane cylopenatane etc.- non aromatic Also cyclic compound may be anti atomatic like cyclohex-2,4 -ene etc. Hope it may help you.

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Soumya Kumari 6 years, 5 months ago

Gibe nahi give

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ANSWER

Why does HBr while reacting with H2SO4 is not oxidized to Br2 while HI is oxidized to I2??

Posted by Preetinder Garcha 6 years, 5 months ago

CBSE > Class 12 > Chemistry

1 answers

Aditya Pahuja 6 years, 5 months ago

Because iodine is a strong oxidisting agent hence oxidises it self to i2

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ANSWER

Can we store copper sulphate solutions in zinc pot

Posted by Ravish Kumar 6 years, 5 months ago

CBSE > Class 12 > Chemistry

3 answers

Bhavya Goswami 6 years, 5 months ago

No because zinc reacts with copper

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Ďãřşháñăã Yadav ? ? ? 6 years, 5 months ago

no we can't store copper sulphate in zinc pot becz zinc is more reactive than copper it will displace copper from copper sulphate solution and make zinc sulphate.

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I Harjeet Dhillon 6 years, 5 months ago

No... Because Zn is more reactive than Cu.

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ANSWER

Alkyl halide though polar are immiscible in water?

Posted by Gurmeet Kaur 6 years, 5 months ago

CBSE > Class 12 > Chemistry

1 answers

Sia ? 6 years, 5 months ago

To be miscible with water, the solute-water force of attraction must be stronger than the solute-solute and water-water forces of attraction. Alkyl halides are polar molecules and so held together by dipole-dipole interactions. Similarly, strong H-bonds exist between the water molecules. The new force of attraction between the alkyl halides and water molecules is weaker than the alkyl halide-alkyl halide and water-water forces of attraction. Hence, alkyl halides (though polar) are immiscible with water.

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ANSWER

Plz help me to choose the topic for speech tomorrow from chemistry plz koi simple or easy topic bata do koi

Posted by Preeti Baliyan 6 years, 5 months ago

CBSE > Class 12 > Chemistry

5 answers

Me Hamlik 6 years, 5 months ago

Effect of dilution on conductance ,, Easy and vary good topic to describe,

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Priya Dharshini 6 years, 5 months ago

Ya take some great scientist discovery, chapter 6 metallurgy - extraction of minerals... take some inorganic chapter and explain those important concepts..... just make sure u choose any topic u know v.good and be as a lecturer and speak..

1Thank You

Shreya Dixit 6 years, 5 months ago

About scientists /chemist who contributed a lot in chemistry

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Ďãřşháñăã Yadav ? ? ? 6 years, 5 months ago

ya environmental chemistry will be easy or u can choose polymers. nd chemistry in our everyday life is also popular nd easy one.

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Sajid Ali 6 years, 5 months ago

About environmental chemistry will be easy for you.

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ANSWER

Draw the structure of semicarbazone of cyclopentaone

Posted by Justin Bieber 6 years, 5 months ago

CBSE > Class 12 > Chemistry

2 answers

Anubhav Anand 6 years, 5 months ago

Baskstene structure

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Anubhav Anand 6 years, 5 months ago

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ANSWER

What is the diff. between hinsberg and mustard oil test?

Posted by Rajat Barwar 6 years, 5 months ago

CBSE > Class 12 > Chemistry

0 answers

ANSWER

Why does no2 dimerises explain briefly

Posted by Hoi An Half 6 years, 5 months ago

CBSE > Class 12 > Chemistry

1 answers

Sia ? 6 years, 5 months ago

NO₂ is an odd electron (7+2×8=23) molecule. In the valence shell, N has seven electrons and hence is stable. To become stable by having 8 number electrons in the valence shell, it undergoes dimerisation to form N₂O₄.
2NO₂ ═ N₂O₄

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