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practical exam for VIVA questions-answers. B.Sc. -M.Sc. practical exam note.

 VIVA VOCE               

practical exam for VIVA questions-answer. B.Sc. -M.Sc. practical exam note.

 

1. Definition of organic compound :

  • Organic compound defined as the substances, which contain Carbon and Hydrogen with or without some more elements like Nitrogen, Sulphur, Helogen etc.

         

2. Why a Diethyl ether a good choice for an organic solvent in an acid-base extraction?

  • Diethyl ether is considered a good organic extracting solvent because it has a low polarity, water being very polar. So the organic compounds dissolve more readily in Diethyl ether than water.

     3. Huckel's rule :

  • In order to be aromatic, a molecule must have a certain number of pi electrons (electrons with pi bonds, or lone pairs within p orbitals) within a closed loop of parallel, adjacent p orbitals.

                           in 4n+2   n≠0


4. Process of solubility test :

  1. For Acid :

RCOOH + NaHCO3 → RCOONa + H2O + CO2

                                        sodium salt of

                                        carboxylic acid

RCOONa + HCl → RCOOH + NaCl

  1. For Base :

R-NH2 + HCL → R-NH3+-Cl-

                        Amine hydro-

                            chloride salt

R-NH3+-Cl-  + NaOH → R-NH2 + NaCl + H2O

  1. For Phenol :

Ar-OH + NaOH → Ar-ONa + H2O

                                Sodium

                                   phenoxide

Ar-ONa + HCl → Ar-OH + HCl


5. Chemistry of Lassaign Test :

  • Na is highly reactive metal that's why it is used in lassaign test.

  • When the organic compound is heated with molten sodium metal the  metal causes braking of covalent bond present in organic compound and compound is converted to inorganic salt which is readily soluble in water and gives various specific colour reaction for elements with different reagents. 

  1. For Nitrogen (N) :

Fused Na + org. comp. → NaCN

                           covalent             ionic

                              bond                bond

NaCN + FeSO4 → Na4[Fe(CN)6]

                                   (green colour)

Na4[Fe(CN)6] + FeCl3 → Fe4[Fe(CN)6]

                                                  (blue colour)

  1. For Sulphur (S) : 

 Na + S Na2S

 Na2S + Na2[Fe(CN)5NO] Na4[Fe(CN)5NOS]

           Sodium nitroprusside          (black colour)

  1. For Halogen (X) :

Na + X NaX

NaX + AgNO3 AgX + NaNO3


6. Definition of derivative :


7.  Which mixture is totally soluble in 20% NaOH ?

  • Acid + Phenol

  • Phenol dissolve only in 20% NaOH while acid dissolve in 20% NaOH as well as in saturated NaHCO3.


8. The acid in which -COOH group absent even though known as acid.....                                                   

                    

                              Picric acid                                                             Sulphanilic aacid


9. Test of -COOH group...

  • Compound + satu. NaHCO3 → effervances of CO2 gas

  • (Acid + Alcohol) heat it in presence of dil. H2So4 → Smell of ester (sweet smell)



10. Test of -OH (Phenolic)...

  • Pthaline test : substance + 0.1 gm of pthalic anhydide + 1-2 drops of H2SO4. Fuse the mass, cool and pour in  2 ml of NaOH solution and dilute with water.

  • Libermann's test : 0.05 gm substance + crystals of NaNO2; heat, cool, add 0.2 ml dil. H2SO4; shake and dilute with water. different colour with excess of NaOH.


11. Concept of ortho (o), meta (m), pera (p)...

  •              ortho : 1:2                 meta : 1:3                      pera : 1:4                

   

12. Ortho - Pera directing group :

  • -Cl , -Br, -OH, -CH3, -NH2 etc.


13. Meta directing group :

  • -NO2, -SO3H, -CCl3


14. Defination of 1o, 2o & 3o alcohol :

  • 1o : -OH attached carbon joint with another one carbon atom 

ex : CH3CH2OH

  • 2o : -OH attached carbon joint with another two carbon atom

ex : CH3CHOHCH3

  • 3o : -OH attached carbon joint with another three carbon atom

  


15. Why azo-dye test perform at 0-5oc ?

  • because diazonium salt is unstable at higher temprature.


16. Definition of 1o, 2o & 3o  Amine :

  • 1o Amine : 1 hydrogen of NH3 is substituted by one R or Ar group.           R-NH2

  • 2o Amine : 2 hydrogen of NH3 is substituted by two R or Ar group.        R-NH-R'

  • 3o Amine : 3 hydrogen of NH3 is substituted by three R or Ar group. R-N-R'

     |

     R"


17. Why AgNO3 solution keep in amber colour bottle ?

  • To stop decomposition of AgNO3 in the presence of sunlight.


18.Name of liquid having bitter almond smell :

  • Nitrobenzene


19. Which compound shows silver mirror test?

  • aldehyde

20.  Which compound shows iodoform test ?

  • ketone


21. Is Benzene unsaturated? Why?

  • no, benzene is not unsaturated because in benzene, double bonds are not stable but continuously in moving condition means delocalised.


22. In chloroform benzene is absent even though burns with shooty flame, why ?

  •  In chloroform % composition of carbon is very high so it gives shooty flame.


23. Substitution reaction :

  •  An atom or group of atom in an organic compound is substituted by different atoms or group of atom in reaction is called substitution reaction.


24. Addition reaction :

  • During a chemical reaction with a molecule containing a double bond or a triple bond, if the Ï€ bond of the double bond or a triple bond breaks and a new compound is formed by addition of another molecule, the reaction is called addition reaction.

25. Elimination reaction :

  • In an organic reaction, atom or group of atoms is removed from adjacent carbon atom resulting in the formation of additional new bond between two cabon atom, the reaction is known as elimination reaction.

26. Rearrangement reaction :

  • In a molecule of organic compound the migration of atom or group of atoms to another position takes place within the same molecule under suitable conditions, the reaction is called rearrangement reaction.


27. Isomers :

  • An isomer is a molecule with the same molecular formula as another molecule, but with a different chemical structure. Isomers contain the same number of atoms of each element, but have different arrangements of their atoms.

          28. Hybridisation in Alkane, Alkene & Alkyne:

  • Alkane : SP3

  • Alkene: SP2

  • Alkyne: SP

29. Alkylation :

  • Alkylation is define as the introduction of an alkyl radical by    

       substitution and addition in organic compound.


 https://upload.wikimedia.org/wikipedia/commons/thumb/f/f4/Benzene_Friedel-Crafts_alkylation-diagram.svg/500px-Benzene_Friedel-Crafts_alkylation-diagram.svg.png


30. Esterification :

  • Esterification is one of the unit process by which esters are formed. 

http://www.chemguide.co.uk/organicprops/alcohols/estergeneq.gif


31. Helogination :

  • Helogination process is defined as the process of introduction of one or more halogen atom into in an organic compound.

RC6H5 + X2 → HX + RC6H4X


32. Hydrolysis:

  • Usually hydrolysis is a chemical process in which a molecule of water is added to a substance

33. Oxidation and reduction :

  • Oxidation is gain of oxygen.

  • Reduction is loss of oxygen.

http://www.chemguide.co.uk/inorganic/redox/redoxeqtn1.gif


34. Nitration :

  • Nitration is a general class of chemical process for the introduction of a nitro group into an organic chemical compound.  


35. Sulphonation :

  • Sulphonation is defined as a process in which introduces sulphonic acid group or the corresponding salt or sulphonyl halide group into an organic compound.

                  RCH2COOH + SO →  RCH2(SO2OH)COOH

36. Structure of Penicilline :



37. Normality:

  • Normality could be defined as the number of gram equivalents of a solute present per litre (dm3) of the solution at any given temperature and It is expressed as N.

  • Normality = Equivalents of solute / liters of solution


38. Molarity :

  • Molarity is an unit for expressing the concentration of a solute in a solution, and it is calculated by dividing the moles of solute by the liters of solution. 

  • molarity = moles of solute / liters of solution.

              

  39. Molality : 


40. What are the various types of chromatography techniques?

  • GLC, Gas Liquid Chromatography

  • TLC, Thin Layer Chromatography

  • Column Chromatography

  • Paper Chromatography


41. Why paper chromatographic technique is preferred over other methods?

  • Chromatographic technique is used to separate the components of a mixture when the mixture is present in a very small amount, even a drop.


42. Why the substance dissolve in HCl for flame test?

  • All salts converted into their volatile chlorides treatment with conc. HCl. These volatile chlorides gives characteristic coloured flame in flame test.


43.Why the fusion tube and sodium metal both should be dry?

  • Because Na is very reactive metal; it can react with water.


44.What is a spot test?

  • These test are done on glass slide or filter paper and product of the reaction observed as a coloured spot. This test required trace amount of sample.

45.Why aliphatic compounds burn with non-sooty flame?

  • Aliphatic compounds burn with non-sooty flame because  there compounds contain less proportion as of carbon.

46. Why we don't get ppt on addition of AgNO3 in chloroform?

  • Chloroform is covalent compound. It does not contain Cl̄ ion. Therefore Ag+ from AgNO3 can't give ppt with chloroform. 

47. How CO2 and SO2 gas can be detected?

  • Organic colour of acidic dichromate solution to green with reaction of SO2 gas where CO2gas gives no effect.

48.Which negative radicals can be detected by using of chloroform?

  • Cl-, Br-, I-


49.Which organic compounds give yellow ppts by adding NaOH and I2?

  • -COCH3 group contain


50. How will you distinguish between alcohols and phenol?

  • Phenols are soluble in 20% NaOH solution but alcohols are not.


51. Why should ferrous sulphate solution be fresh and saturated?

  • A dilute ferrous sulphate solution after a long time oxidises to basic ferric sulphate which is useless in analysis.

52.What is functional group?

  • The atom or a group of atom which is responsible for the organic reaction called functional group -Cl, -COOH, -NO2, -NH2 etc. are the example of functional group.

53. Name only the fun. group which contain carbonyl group:

  • -CHO, -CO-R, -COOH, -COOR, -COCl, -NHCOCH3, -CONH2

54. Why Pb+2 include both in first and second group?

  • In first group Pb+2 is precipitated as PbCl2. which is slightly soluble in acidic medium. Therefore some quantity of Pb+2 is remain in the solution. In second group Pb+2is precipitated as PbS.

54. Preparation of sodium cobaltinitrite:

  • Take NaNo2 solid and add Co(NO3)2 solution and add little acetic acid. This is the reagent used for the detection of K+.

55.Concept of dextro and levo:

  • The prefix dextro comes from the Latin word dexter. It means "on the right side" or "to the right".

  • The prefix levo comes from the Latin word laevo. It means "on the left side" or "to the left".

  • We see these terms when we talk about chiral molecules rotating the plane of polarized light.

  • If the plane of polarized light is rotated clockwise as it approaches the observer (to the right if you are steering a car), the molecule is dextrorotatory (d).

  • If the plane of polarized light is rotated counterclockwise (to the left), the molecule is levorotatory (l).

 

www.rpi.edu


56. Chirality:

  • Stereoisomers are isomers that differ in the spatial arrangement of atoms, rather than the order of atomic connectivity. One of the most interesting types of isomer is mirror-image stereoisomers, a non-superimposable set of two molecules that are mirror images of one another. The existence of these molecules is determined by concept known as chirality. The word "chiral" was derived from the Greek word for hand, because our hands are good example of chirality since they are non-superimposable mirror images of each other.

57. Chiral carbon:

  • An asymmetric carbon atom (chiral carbon) is a carbonatom that is attached to four different types of atoms or groups of atoms.

PREPARATION OF SOLUTION FOR ORGANIC SEPARATION :


1. Neutral FeCl3 :

  • Take FeCl3 soln and add dropwise dil. NH4OH till brown ppt of ferric hydroxide just begins, Heat the solution and just remove the excess of ammonia. Thus reddish clear soln obtained used as neu. FeCl3

2. Liebermann's test :for phenolic compound

  • 0.05 gm sub. + crystal of NaNO2; heat,cool. add 0.2 ml H2SO4: shake dilute with water: green, blue or black colour, with excess of NaOH soln colour change

Substance

NaNO2+H2SO4

water

NaOH

Phenol

Intense blue or green

Red

Intense blue or green

o-Cresol

''

Red

''

m-Cresol

''

Brown

Dirty green

Resorcinol

''

Red

Brownish red

p-Cresol

Red or dirty brown

-

-

α-Napthol

Intense green

-

-

β-Napthol

Brown black

-

-


3. Tollen's reagent :

  • AgNO3 + NaOH till the precipitation is completed + NH4OH for dissolve the ppt.

           4. Fehling a :

  • Dissolve 34.6 gm of CuSO4.5H2O crystals in 500ml water.

           5. Fehling b :

  • Dissolve 173 gm of sodium pottasium tartarate and 50 gm of NaOH in water and make it 500 ml by adding more water.

  • sodium pottasium tartarate is known as Rochelle salt.

  • act as chelating agent.

6. Pthalin test :

  • sub. + 0.1 gm pthalic anhydride + 1-2 drop of H2SO4.fuse the mass , cool and pour in 2 ml of NaOH soln. and dilute with water. coloured flourosence is produced.

o-cresol or phenol

red

m-cresol or catechol

Blue

Resorcinol or α-Napthol

Green

β-Napthol

Faint green

p-cresol

No colouration


                     7. Azo-dye test :

  • T.T : 1 β-Napthol in NaOH

T.T : 2 NaNO2 in water

T.T : 3 compound in dil. HCl


cool the test tube then add 2nd t.t in 3rd t.t the add 1st t.t in 3rd.


8. Muliken-Barker test :

  • comp. + 2ml C2H5OH + 1ml CaCl2 soln. + Zn dust. boil & filter.Add tollense reagent tp filtrate after cooling: black or gray ppt.

9. Molische's test :

  • 0.05 gm of sub + 1 ml H2O + 2 drops of 10% alcoholic              β-Napthol  soln. then add 1 ml conc.H2SO4 through sides of the testtube. Gives red ring changing to violet at the interface of the two liquids.

10.Silver mirror test :

  • comp + lead acetate + NaOH (excess): black silver mirror

  • Aldehyde is oxidised and AgNO3is reduced.

      11. Nesseler reagent:

  • In a clean test tube take 3-4 drops of HgCl2 solution and add KI dropwise till orange ppts formed resissolves. Add NaOH soln. in slight excess, shake well. This is the reagent.


:AMINO ACID:

  • AMINO ACID :

An organic that contains an acids fun. group and an amine fun. group on adjecent carbon atom is called amine acid.

Ex. Lysine, glycine, tryptophan.

  • EASSENTIAL AMINO ACID:

Any of various amino acids that are required for normal health and growth which can not be synthesised in body are known as essential amino acid.

Ex. Histidine, Isoleucine, leucine, lysine, methionine, Threonine, valin.

  • NON-ESSENTIAL AMINO ACID:

Any of various amine acids that are required for normal health and growth which can be synthesised within body or derived in from essential amino acid are known as non essential amino acid.

Ex. Alanine, arqinine, aspartic acid, cyteine, glycine, serine, asparqine.


  • ACIDIC AMINO ACID:

In this type of amino acid the f.group that joined as R is acidic in nature.

Ex. Aspartic acid, Glutamic acid


  • BASIC AMINO ACIDS:

In this type of amino acid the fun. group that joined as R is basic in nature.

Ex.Lysine, Argenine


  • NEUTRAL AMINO ACID:

In this type of amino acid the fun. group that joined as R is neutaral in nature.

Ex. Glysine, Alanine


PENICILLINE

  • MOLECULAR FORMULA: C16H20N2(C16H18N2O4S)2

  • MOLECULAR WEIGHT: 909.12 gm/mole

  • Penicilline can not be taken by mouth corally because in stomach it is hydrollised with acid.

  • It is active on bacteria and germs.

  • BRAND NAME : Benzyl penicilline , Benzathin benzyl penicilline , Benzathin penicillin-G

  • CATEGORY: Antibacterial (Antibiotic)

  • FOUNDER: Alexander flaming (from fugs)

  • PURE PENICILLINE FOUNDER BY : Flaming Fore & Ernest Chain

  • INDUSTRIAL MANUFACTURE: Penicilline Crysogenone (enzyme)

  • DOES: Orally, 225 mg to 450 gm in every  6:00 hours by intramolecule injection.

  • POTENCY: 1000000 unit (bottle)

  • DEFFINATION OF POTENCY: A given drug stop the growth of certain numbers of bacteria or germs in certain period of time is known as potency of drug.

  • ANTIBIOTICS: A drug that is used to kill harmful bacteria and to cure injections is known as antibiotic. 








Examples of Simple Unbranched Alkanes

Name

Molecular
Formula

Structural
Formula

Isomers


Name

Molecular
Formula

Structural
Formula

Isomers

methane

CH4

CH4

1


hexane

C6H14

CH3(CH2)4CH3

5

Ethane

C2H6

CH3CH3

1


heptane

C7H16

CH3(CH2)5CH3

9

Propane

C3H8

CH3CH2CH3

1


octane

C8H18

CH3(CH2)6CH3

18

Butane

C4H10

CH3CH2CH2CH3

2


nonane

C9H20

CH3(CH2)7CH3

35

Pentane

C5H12

CH3(CH2)3CH3

3


decane

C10H22

CH3(CH2)8CH3

75



MENDELEEVE PERIODIC TABLE


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