Chapter 2nd

on Sunday 18 December 2011
Chapter No. 2

EXPERIMENTAL TECHNIQUES IN CHEMISTRY

MCQs
Q.1         Science of the chemical characterization is stand under the heading of                         
                (a)           industrial chemistry             (b)           experimental chemistry
                (c)           analytical chemistry           (d)           physical chemistry
Q.2         Several types of filter media are used for filtration depending on
                (a)           nature of reaction                (b)           nature of reactants
                (c)           nature of precipitate           (d)           nature of filter paper
Q.3         Filtration by a glass funnel and filter paper is very
                (a)           time consuming                   (b)           difficult
                (c)           fast                                         (d)           accurate
Q.4         Date of filtration through conical funnel can be considerably increased by using
                (a)           fine filter paper                    (b)           ordinary filter paper
                (c)           fluted filter                            (d)           under suction crucible
Q.5         Gooch crucible is used to filter the solution of
                (a)           K2Cr2O7                   (b)           KMnO4
                (c)           KOH                                       (d)           under suction crucible
Q.6         Basic principles of crystallization is that solute should be soluble in a suitable solution at
                (a)           freezing temperature           (b)           room temperature
                (c)           high temperature (d)           low temperature
Q.7         Premature crystallization of solution of filter paper or in funnel can be avoided
                (a)           filtering hot saturated solution using hot funnel
                (b)           filling warm solution
                (c)           quick filtration
                (d)           filtering cold solution
Q.8         Safe and reliable method of drying crystal in through
                (a)           pressing it between folds of filter paper
                (b)           drying it in oven
                (c)           evaporation of solution
                (d)           vacuum desiccator
Q.9         In solvent extraction solute can be separated from solution by shaking the solution with solvent which the solute is
                (a)           more soluble                         (b)           partially soluble
                (c)           insoluble                                (d)           soluble at high temperature
Q.10       Repeated extraction using small portions of solvent are more
                (a)           accurate                                (b)           efficient
                (c)           slow                                        (d)           rapid
Q.11       To achieve a good separation the two liquids are gently shaken to increase their area of
                (a)           miscibility                              (b)           separation
                (c)           contact                                  (d)           solubility
Q.12       Chromatography in which stationary phase is solid is called
                (a)           partition chromatography
                (b)           paper chromatography
                (c)           high pressure
                (d)           adsorption chromatography
Q.13       Chromatography involves these distribution of a solution between
                (a)           two stationary phase
                (b)           two mobile phase
                (c)           a stationary phase and a mobile phase
                (d)           two stationary and two mobile phase
Q.14       Chromatography in which the stationary phase is liquid is called
                (a)           partition chromatography
                (b)           descending chromatography
                (c)           column chromatography
                (d)           Adsorption chromatography
Q.15       In paper chromatography the rate at which solutes move depends on
                (a)           distribution law                    (b)           distribution coefficients
                (c)           law of partial pressure        (d)           law of specific proportion
Q.16       Solvent extraction is an equilibrium process and it is controlled by
                (a)           law of mass action              (b)           the amount of solvent used
                (c)           distribution law                    (d)           the amount of solute
Q.17       The comparative rates at which the solutes move in paper chromatography depend on
                (a)           the size of paper used
                (b)           Rf values of solutes
                (c)           temperature of the experiment
                (d)           size of the chromatographic tank used
Q.18       A filtration process could be very time consuming if it were not aided by the gentle suction, which is developed
                (a)           if the paper covers the funnel up to its circumference
                (b)           if the paper has got small sized pores in it
                (c)           if the stem of the funnel is large so that it dips into the filtrate
                (d)           if the paper fits tightly
Q.19       Solvent extraction method is particularly useful technique for separation, when product to be separated is
                (a)           non–volatile or thermally unstable
                (b)           volatile or thermally stable
                (c)           non volatile or thermally stable
                (d)           non–volatile or thermally unstable
Q.20       During the process of crystallization, the hot saturated solution
                (a)           is cooled very slowly to get large sized crystals
                (b)           is cooled at a moderate rate to get medium sized crystals
                (c)           is evaporated to get the pure crystals of the product
                (d)           is mixed with an immiscible liquid, to get the pure crystals of the product
Q.21       Aqueous solution of iodine is prepared first by dissolving which compound in water
                (a)           KBr                                         (b)           KI
                (c)           KCl                                         (d)           NaCl
Q.22       The meaning of chromatos
                (a)           colour writing                        (b)           colour writing
                (c)           colour forming                     (d)           colour spreading
Q.23       Which is not common way of carrying chromatography
                (a)           ascending                              (b)           descending
                (c)           radial/circular                       (d)           spreading irregularly
Q.24       In paper chromatography the stationary phase is
                (a)           water                                      (b)           organic liquid
                (c)           inorganic liquid                    (d)           none of the above
Q.25       In paper chromatography the mobile phase is
                (a)           organic liquid                        (b)           water
                (c)           inorganic liquid                    (d)           none of the above


                                                                            ANSWERS

Questions
1
2
3
4
5
Answers
c
c
a
c
b
Questions
6
7
8
9
10
Answers
c
a
d
a
b
Questions
11
12
13
14
15
Answers
c
d
c
a
b
Questions
16
17
18
19
20
Answers
c
b
d
d
b
Questions
21
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25
Answers
b
a
d
a
a



SHORT QUESTIONS WITH ANSWERS

Q.1         Define analytical chemistry ?
Ans.
                The branch of chemistry which deals with the qualitative and quantitative analyses of sample is called analytical chemistry.
Q.2         Define analysis and analyte ?
Ans.        Analysis:
                The determination of the composition of a sample is called analysis.
Analyte:
                The sample being analyzed is called analyte.
Q.3         Differentiate between qualitative and quantitative analysis. What is analytical data ?
Ans.        Qualitative analysis:
                The analysis which deals with the detection or identification of the elements present in a compound is called qualitative analysis. It includes salt analysis and detection of functional groups.
Quantitative analysis:
                The analysis in which the relative amounts of constituents are estimated is called quantitative analysis. For example combustion analysis.
Analytical data:
                The results obtained by qualitative and quantitative analysis are called analytical data.
Q.4         Name the experimental techniques for purification of substances ?
Ans.
                (1)           Filtration.
                (2)           Crystalization.
                (3)           Sublimation.
                (4)           Solvent Extraction.
                (5)           Chromatography.
Q.5         Define filtration ?
Ans.
                The process in which the insoluble particles are separated from the liquid by passing through several types of filter media is called filtration.
Q.6         Define the following.
                (i)  Filter     (ii)  Filtrate     (iii)   Residue  
                (iv)  Filter Medium.
Ans.        Filter:
                Any water insoluble porous material having measurable degree of rigidity is called filtrate.
Filtrate:
                The liquid which after passing the mixture through filter medium is collected is called filtrate.
Residue:
                The solid left behind on the filter medium during filtration is called residue.
Filter medium:
                The porous material used for filtration is called filter medium. It may be filter paper, cotton, woven wire, cloth etc.
Q.7         Give reasons that the funnel in filtration should be several inches long ?
Ans.
                The stem of the funnel should be several inches long so that it can extend a few centimeters down into the receiving beaker and tip should touch the side of beaker in order to avoid splashing.



Q.8         Discus the points should be kept in mind during the folding of the filter paper ?
Ans.
1.             Filter paper should be folded twice. The first fold should be along the diameter, and the second fold should be such that edges do not quite match.
2.             Folded filter paper should be open slightly on the larger section. This provides a cone with three fold thickness half way and one thickness the other half way round.
3.             The apex angle is greater than 60o.
4.             The paper may be inserted in to 60 degree funnel moistened with water and firmly pressed down.
Q.9         Rate of filtration through funnel can be increased by using a fluted filter paper why ?
Ans.
                A fluted filter paper is prepared by folding ordinary filter paper in such a way that fan like arrangement with alternate elevation and depression at various folds is formed.
Q.10       Differentiate b/w Gooch crucible and sintered glass crucible.
Ans.
            (i)      The filtering process can be done of the Gooch crucible is placed in suction filtering apparatus. But in filtration by sintered glass crucible no preparation is needed.
           (ii)      The reagents which react with paper e.g. HCl, KMnO4 etc. Cannot be filtered through Gooch crucible. But reactive solution like HCl,  KMnO4 can be filtered with out any alteration in the sintered crucible.
          (iii)      Gooch Crucible for filtration of such types of precipitates which need to be heated at high temperature. But in sintered crucible while collecting the residue there is no contamination of filter paper.



Q  .11     Define crystallization.
Ans.
                The removal of a solid from solution by increasing its concentration above the saturation point in such a way that the excess solid separates out in the form of crystals is called crystallization.
Q.12       What is the principle of crystallization?
Ans.
                The basic principle of crystallization is the fact that solute should be soluble in a suitable solvent at high temperature and the excess amount of the solute is thrown out as crystals when it is cooled.
Q.13       What is the objective of crystallization ?
Ans.
                The preparation of chemical compound usually has a crude product and there is a need to purify it by crystallization from a suitable solvent
Q.14       Name the solvents commonly used for crystallization.
Ans.
                The solvents which are mostly used for crystallization are, water, rectified spirit, (95% ethanol), absolute ethanol, diethylether acetone, chloroform, carbon tetrachloride, acetic acid and petroleum ether.
                If none of the above solvents is found suitable for crystallization, a combination of two or more miscible solvents may be employed.
Q.15       Describe the preparation of saturated solution ?
Ans.
                After selecting a suitable solvent the substance is then dissolved in a minimum amount of solvent and is heated directly or on a water bath with constant stirring. Add more solvent to the boiling solution, if necessary until all the solute has dissolved.
Q.16       What are the safe and reliable methods for drying the crystals ?
Ans.
1.             Drying through vacuum desiccator
                A safe and reliable method of drying crystals is through a vacuum desiccator. In this process the crystals are spread over water glass and kept in a vacuum desiccator for several hours. In the desiccator CaCl2, silica gel or  P2O5 are used as drying agents
2.             Drying in an oven
                The crystals are dried in an oven provided the substance does not melt or decompose on heating at 1000c.
Q.17       How the undesirable colours are removed in crystals ?
Ans.
                Sometimes during the preparation of crude substance, the colouring matter or resinous products affect the appearance of product and it may appear coloured. Such impurities are conveniently removed by boiling the substance in a solvent with the sufficient quantity of finely powdered animal charcoal and the pure decolourized substance crystallizes out from the filtrate on cooling.
Q.18       Define mother liquor? How the crystals can be obtained from mother liquor ?
Ans.
                The remaining solution after the formation of crystals is called mother liquor.
1.             The mixture of crystals and mother liquor is filtered through a Gooch crucible connected with a vacuum pump.
2.             After full suction to drain the mother liquor as effectively as possible. When the filter is rigid enough it is pressed carefully but by firmly by means of a cork in order to drain the left over liquid.
3.             The crystals are then washed will small portion of cold solvent repeating this process many times.
4.             The crude mother liquor is concentrated by evaporation and it get good crops of crystals.
Q.19       Define sublimation.
Ans.
                When substance is heated it goes directly in to vapours without passing through the liquid state and vapours thus formed are condensed back it form the solid on cooling once again with out passing though liquid state is called sublimation.
                Examples of such solids are iodine, ammonium chloride, naphthalene , benzoic acid and camphor.
Q.20       What is sublimand ?
Ans.
                The compound which is sublimed is called sublimand.e.g In the mixture of benzoic acid in sand, benzoic acid is sublimand.
Q.21       What is the main function and limitation of  sublimation ?
Ans.
                By this process of sublimation certain substance can be purified. It is only suitable for those substances which have high V.P than their melting point.
Q.23       What is solvent extraction? When it is applicable ?
Ans.
                It is a technique, in which a solute can be separated from a solution by shaking the solution with a solvent in which the solute is more soluble and added solvent does not mix with the solution.
                The technique of solvent extraction is mostly applied to separate organic compounds from water.
Q.24       What is the most common solvent in solvent extraction method? Why we choose ether in solvent extraction?
Ans.
                The common solvent is ether in the solvent extraction we choose ether in the solvent extraction because ether layer is separated and organic product is obtained by evaporating ether repeated extractions using small portions of solvent ether are more efficient than using single but larger volume of solvent.
Q.25       State distribution law or partition law ?
Ans.
Distribution law:
                This law states that a solute distribute itself between two immiscible liquids in a constant ratio irrespective of the amount of solute added.
                The ration of the amounts of solute dissolved in two immiscible liquids at equilibrium is called distribution coefficient.
Distribution coefficient KD =
Q.26       Discuss the importance of solvent extraction method.
Ans.
Separation can be carried out on macro as well as micro level.
2.             There is no need of any instrumentation except separating funnel.
3.             It can be used for preparation, purification and analysis on all scales of working.
Q.27       Define chromatography? What is the principle of chromatography?
Ans.
                Chromatography is a technique used for separating the components of a mixture. These components are separated due to the relative affinity for  stationary phase and mobile phase.
Q.28       Define and explain, stationary phase and mobile phase.
Ans.
Stationary phase:
                The phase over which mobile phase flows in chromatography is called stationary phase.
                The stationary phase may be a solid or liquid supported on a solid. It adsorbs the mixture under separation.
                Examples of stationary phase are silica gel, alumina and filter paper etc.
Mobile phase:
                The solvent or mixture of solvents for this separation of components is called mobile phase.
                The mobile phase may be liquid or gas and while passing one the stationary phase, competes with it for the constituents of mixture.
                Examples of mobile phase are, water, ethanol, ethanoic acid and propanone (acetone) etc.



Q.29       What is the principle of chromatography ?
Ans.
                The principle involved in the chromatography depends upon the relative solubilities of the components, between the two phases. The distribution of the components mixture between the two phases is governed by the distribution coefficient KD, which is ratio of component in mobile phase to the concentration of component in stationary phase.
                KD  = 
Q.30       What is the importance of distribution coefficient ?
Ans.
(i)            The component of a mixture with a small value of KD mostly remains in the stationary phase as moving phase flows over it.
The component with a greater value of KD remains largely dissolved in the mobile phase and passes over the stationary phase quickly.
Q.31       Differentiate between adsorption chromatography and partition chromatography ?
Ans.        Adsorption chromatography:
                Type of Chromatography in which the stationary phase is  solid, is called adsorption chromatography. Example of this chromatography is Thin layer chromatography.
Q.32       What is partition chromatography ?
Ans.        Partition chromatography:
                Type of Chromatography in which the stationary phase is liquid is called partition chromatography. Example of this chromatography is paper chromatography.
Q.33       Define and explain paper chromatography ?
Ans.
                It is a technique of partition chromatography in which the stationary phase is water adsorbed on a paper. The mobile phase is usually an organic liquid.
                In paper chromatography the adsorbed water behaves as an immiscible liquid towards the mobile phase, which passes over the paper.
Q.34       Name the different ways of paper chromatography.
Ans.
                There are three ways of carrying out paper chromatography.
(i)            Ascending chromatography
(ii)           Descending chromatography
(iii)          Radial/Circular chromatography.
Q.35       What do you mean by Rf value?
Ans.
                Each component has specific retardation factor called Rf value. Rf value is related to distribution coefficient and is given by
Rf  = 
Q.37       What is chromatogram ?
Ans. Finished or Devolped paper obtained after Chromatography is called Chromatogram:
Q.38       Name the types of chromatography on the basis of phase.
Ans.
                There are four types of chromatography.
            (i)      Liquid–liquid chromatography
           (ii)      Liquid–solid chromatography
          (iii)      Gas–liquid chromatography
          (iv)      Gas–solid chromatography
Q.39       Give uses of chromatography.
Ans.
                The techniques of chromatography is very useful in organic synthesis for separation, isolation, and purification of the products.
Mostly used for the separation of amino acids.
Q.40       Why is there a need to crystallize the crude products ?
Ans.
                When a chemical compound is synthesised, it is crude product. Therefore, there is need to purify the compound. This is done by crystallizing the compound.
Q.41       A water soluble organic compound aspirin is prepared by the reaction of salicylic acid with a mixture of acetic acid and acetic anhydride. How will you separate the product from the reaction mixture ?
Ans.
                During the preparation of aspirin, it is obtained as only liquid which can be separated by solvent extraction technique using a non–polar solvent like CCl4 and mixture is transferred to separating funnel where only layer is separated.
Q.42       A solid compound is soluble in water as well as in chloroform. During its preparation it remains in aqueous layer. Describe a method to obtain it from the layer.
Ans.
                The compound can be extracted by solvent extraction technique. As it is mentioned that compound is soluble in polar solvents (water, chloroform). If a non–polar solvent is mixed and the mixture is transferred to a separating funnel, where two layers are formed. By separating water layer and evaporating it, organic compound is obtained.
Q.43    why repeated extractions using small portions of solvent are more efficient than using a single but larger volume of solvent?
Ans.
                It has been observed that repeated extractions using small portions of solvent are more efficient than using a single but larger volume of solvent. Because more product is extracted with more extractions using small portions of solvent.
Q.44       Write down the main characteristics of a solvent selected for the crystallization of compound.
Ans.
                A solvent should have the following characteristics
1.             It should dissolve a large amount of solute in its boiling part.
2.             It should have not reaction with the solute.
3.             It should neither dissolve the impurities, nor crystallize them with the solute.
4.             It should be perfectly safe to use.
5.             It should be easily removable.
6.             It should be inexpensive.

             TEXT BOOK EXERCISE

Q.1.        Multiple choice questions.
  1. Filtration process could be very time consuming if it were not aided by a gentle suction which is developed:
(a)           if the paper covers the funnel upto its circumference.
(b)           if the paper has got small sized pores in it.
(c)           if the stem of the funnel is large so that it dips into the filtrate.
(d)           if the paper fits tightly.
  1. During the process of crystallization, the hot saturated solution:
(a)           is cooled very slowly to get large sized crystals
(b)           is cooled at a moderate rate to get medium sized crystals
(c)           is evaporated to get the crystals of the product.
(d)           is mixed with an immiscible liquid to get the pure crystals of the product.
  1. Solvent extraction is an equilibrium process and it is controlled by.
(a)           law of mass action
(b)           the amount of solvent used
(c)           distribution law
(d)           the amount of solute
  1. Solvent extraction method is a particularly useful technique for separation when the product to be separated is:
(a)           non-volatile or thermally unstable
(b)           volatile or thermally stable
(c)           non-volatile or thermally stable
(d)           volatile or thermally unstable
  1. The comparative rates at which the solutes move in paper chromatography depend on:
(a)           the size of paper
(b)           Rf-value of solutes
(c)           temperature of the experiment
(d)           size of the chromatographic tank used
Ans:        (i) d         (ii) b       (iii) c      (iv) d      (v) b
Q.2.        Fill in the blanks.
  1. A complete chemical characterization of a compound must include ________.
  2. During filtration the tip of the stem of the funnel should touch the side of the beaker to avoid ________.
  3. A fluted fuller paper is used to ________ the process of filtration.
  4. A solvent used for crystallization is required to dissolve ________ of the substance at its boiling point and _________ at the room temperature.
  5. Repeated solvent extractions using small portions of solvent are ________.
Ans:        (i) qualitative & quantitative analysis   (ii) splashing   (iii) increase   (iv) large amount, small amount   (v) more efficient
Q.3.        Tick the correct sentences. If the sentence is incorrect, write the correct statements.
  1. A qualitative analysis involves the identification of elements present in a compound.
  2. If the process of filtration is to run smoothly, the stem of the funnel should remain empty.
  3. If none of the solvents is found suitable for crystallization, a combination of two or more immiscible solvents may be used.
  4. A solute distributes itself between two immiscible liquids in a constant ratio of concentrations depending upon the amount of solvent added.
  5. Paper chromatography is a technique of partition chromatography.
Ans:        (i) true   (ii) false   (iii) true   (iv) false   (v) true
Q.4.        Why is there a need to crystallize the crude product?
Ans:        When a compound is prepared in laboratory, it may contain impurities. This impure and un-refined compound is called crude product. It is necessary to purify the crude product. So there is a need to crystallize the crude product.
Q.5.        A water insoluble organic compound aspirin is prepared by the reaction of salicylic acid with a mixture of acetic acid and acetic anhydride. How will you separate the product from the reaction mixture?
Ans:        Aspirin is separated from reaction mixture is added to cold water. The aspirin forms crystals and other products remain in solution. Finally aspirin is filtered from water by sintered glass crucible.
Q.6.        A solid organic compound is soluble in water as well as in chloroform. During its preparation, it remains in aqueous layer. Describe a method to obtain it from this layer.
Ans:        The organic compound can be extracted by solvent extraction. The aqueous solution of compound is mixed with carbon tetrachloride (CCl4). The mixture is put into the separating funnel. Here two layers are formed. The water layer is separated and evaporated to get the compound.
Q.7.        The following figure shows a developed chromatogram on paper with five spots. (i) Unknown mixture X   (ii) Sample A   (iii) Sample B   (iv) Sample C   (v) Sample D
Find out (i) the composition of mixture X   (ii) which sample is impure & what is its composition.
Ans:        The unknown mixture X contains the components B and C. The sample D is impure. It contains components A and C. We should know that a pure sample give only one spot. The samples A and C are pure.
Q.8.        In solvent extraction technique, why repeated extraction using small portions of solvent are more efficient than using a single extraction but larger volume of solvent?
Ans:        The solvent extraction technique is based upon distribution coefficient. The ratio of concentration of a solute dissolved in two immiscible solvents is a constant. It is called distribution coefficient.
In repeated extractions, we can get maximum amount of solute from the other solvent. It is the reason that repeated extractions using small portions of solvent are more efficient than using a single extraction but larger volume of solvent.
Q.9.        Write down the main characteristics of a solvent selected for crystallization of a compound.
Ans:        The process of crystals formation is called crystallization. When a hot saturated solution of a substance is cooled, then crystals of solid substance separate out. It is called crystallization. This process is used for purification of solid compounds. E.g. Purification of Naphthalene. The process of crystallization involves the following steps.
i.              Choice of Solvent:
A suitable solvent is choosen by hit and trial method. An ideal solvent has following properties
  1. It should dissolve maximum amount of solute.
  2. It should not react with solute.
  3. It should not dissolve the impurities.
  4. On cooling, it should form pure crystals
  5. It should be cheap (in-expensive)
  6. It should be easily removable.
  7. Its use should be safe
  8. An inflammable solvent should be heated on water bath. The most common solvents are water, rectified spirit, absolute alcohol, ether, chloroform, acetone, acetic acid, carbon tetra chloride.
ii.            Preparation of Saturated Solution:
The substance is dissolved in minimum amount of solvent. To dissolve more and more solute, the solution should be heated directly or on water bath. The stirring of solution is necessary.
iii.           Filtration:
The hot saturated solution is filtered to remove insoluble impurities. Sometimes premature crystals can form. It can be prevented  by using hot water funnel.
iv.           Cooling:
The hot filtered solution is cooled. The moderate cooling gives the medium sized crystals and slow cooling gives bigger crystals. Sometimes a few crystals of pure solid are added in solution to start the crystallization process.
v.             Collecting the Crystals:
When the crystallization is complete, then mixture of crystals and mother liquor is filtered through Gooch crucible using a vacuum pump. The mother liquor is removed completely by full suction. Then the filter cake is pressed to remove the rest mother liquor. Finally the crystals are washed with small amount of cold solvent. This process is repeated many times till pure crystals are formed. By evaporation of the mother liquor we can get a fresh crop of crystals.
vi.           Drying of Crystals:
                There are three methods for drying the crystals.
a)       Press the crystals between the folds of filter paper. Repeat this process many times method crystals are crushed and fibers of filter paper mix with them.
b)       Dry the crystals at 100oC in an oven. Here solid should not melt or decompose at 100oC.
c)       Spread the crystals over watch glass and keep in a vacuum desiccators for many hours. The drying agents used in desiccators are CaCl2, P2O5, Silica gel.
vii.          Decolourization of Undersirable Colours:
Sometimes crystals become coloured due to impurities. To prevent it, the substance is boiled with animal charcoal. Animal charcoal absorbs the coloured impurity. The pure colourless crystals are formed by cooling the filtrate.
Q.10.      Write down the procedure to separate the mixture of three inks with the help of paper chromatography.
Ans:        Take a 20cm strip of whatman filter paper No 1. The strip is 2.5cm wide. Mark a pencil line 2.5cm from lower end. A spot of mixture inks is placed on pencil line. The separate spots of three pure inks are also placed on the pencil line. Then filter paper is suspended into the tank containing solvent. The lower end of filter paper dips 5-6mm into the solvent. When mobile phase (solvent front) rises 3/4 the paper, then remove it. Every ink gives a coloured band. But the mixture gives three bands. The Rf values of all bands are calculated. In this way we can separate mixture of three inks.


23 comments:

Unknown said...

hi bro r these fsc part 1 11th class chemistry mcqs

Unknown said...

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Anonymous said...

thankyou so very much for that great work

Unknown said...
This comment has been removed by the author.
Unknown said...

sir aoa
sir the text book mcqs of 3rd and 4rth one is wrong as u published
3rd one correct statement is ( two or more missible solvents not immisible )
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4rth one correct satement is ( yes it depends upon the amount of solvent but does not depends on the amount of solute )
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CORRECT IT AS EARLY AS POSSIBLE

NAME : MALIK MUHAMMAD ZAID

Khabar ki Dunia said...

these r awesome

Khabar ki Dunia said...

so gooooooooooooooood

sania saeed said...

better.........

Unknown said...

good MCqs i like it

Unknown said...

just simple

Unknown said...

plz send me the 2nd year notes

Unknown said...

UFO

Unknown said...

Thanx

junaid said...

best

Unknown said...

nice

Unknown said...

awesooom boss

Unknown said...
This comment has been removed by the author.
alfachemistry said...

Drying with Na to remove the alcohol and water, and polymerizing the aldehyde, followed by fractional distillation. Methods for Purification of Commonly Used Solvents

Unknown said...

This is very good work . I prepared my test by learning it.

Unknown said...

Oho hec mcqs ..yaha sa leta ha

Unknown said...

Good collection

Unknown said...

Thanks sir it is very important and helpful once again thank you very much

Unknown said...

Very Good 😍

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