Important questions of biomolecules

BIOMOLECULES

QUESTIONS

VSA TYPE QUESTIONS (1 - MARK QUESTIONS)

1. Name polysaccharide which is stored in the liver of animals.

2. What structural feature is required for a carbohydrate to behave as

reducing sugar?

3. How many asymmetric carbon atoms are present in D (+) glucose?

4. Name the enantiomer of D-glucose.

5. Give the significance of (+)-sign in the name D-(+)-glucose.

6. Give the significance of prefix ‘D’ in the name D-(+)-glucose.

7. Glucose is an aldose sugar but it does not react with sodium hydrogen

sulphite. Give reason.

8. Why is sucrose called invert sugar?

9. Name the building blocks of proteins.

10. Give the structure of simplest optically active amino acid.

11. Name the amino acid which is not optically active.

12. Write the Zwitter ionic form of aminoacetic acid.

13. Name the enzyme which catalyses the hydrolysis of maltose into glucose.

14. Give reason : Amylase present in the saliva becomes inactive in the

stomach.

15. How would you explain the amphoteric behavior of amino acids.

16. Which forces are responsible for the stability of  – helical structure of

proteins.

17. How are polypeptides different from proteins.

18. Which nucleic acid is responsible for carrying out protein synthesis in the

cell.

19. The two strands in DNA are not identical but complementary. Explain.

20. When RNA is hydrolysed, there is no relationship among the quantities of

different bases obtained. What does this fact suggest about the structure

of RNA.

21. What type of linkage holds together the monomers of DNA and RNA.

22. Mention the number of hydrogen bonds between adenine and thymine.

23. A child diagnosed with bone deformities, is likely to have the deficiency of

which vitamin?

24. What is meant by the term DNA fingerprinting?

25. List two important functions of proteins in human body.

26. Name the vitamin responsible for coagulation of blood.

27. Except vitamin B12, all other vitamins of group B, should be supplied

regularly in diet. Why?

28. How is glucose prepared commercially?

29. What is the structural difference between glucose and fructose?

30. What is the difference between an oligosaccharide and a polysaccharide.

31. Give the Haworth projection of D-glucopyranose.

SA (I) TYPE QUESTIONS (2 - MARK QUESTIONS)

1. What are anomers. Give the structures of two anomers of glucose.

2. Write the hydrolysed products of

(i) maltose (ii) cellulose.

3. Name the two components of starch? Which one is water soluble?

4. (i) Acetylation of glucose with acetic anhydride gives glucose

pentaacetate. Write the structure of the pentaacetate.

(ii) Explain why glucose pentaacetate does not react with hydroxylamine?

5. What are vitamins? How are they classified?

6. (i) Why is sucrose called a reducing sugar?

(ii) Give the type of glycosidic linkage present in sucrose.

7. Classify the following as monosaccharides or oligosaccharides.

(i) Ribose (ii) Maltose

(iii) Galactose (iv) Lactose

8. Write the products of oxidation of glucose with

(a) Bromine water (b) Nitric acid

9. State two main differences between globular and fibrous proteins.

10. Classify the following amino acids as neutral, acidic or basic.

(i) HOOC – CH2 – CH (NH2) COOH

(ii) C6H5 – CH2 – CH(NH2) COOH

(iii) H2N – (CH2)4 – CH(NH2) – COOH

11. You have two amino acids, i,e. glycine and alanine. What are the structures

of two possible dipeptides that they can form?

12. What are essential and non essential amino acids? Give one example of

each type.

13. Name four type of intermolecular forces which stabilize 2° and 3° structure

of proteins.

14. Classify the following as globular or fibrous proteins.

(i) Keratin (ii) Myosin

(iii) Insulin (iv) Haemoglobin.

15. What do you understand by

(a) denaturation of protein (b) specificity of an enzyme.

16. On electrolysis in acidic solution amino acids migrate towards cathode

while in alkaline solution they migrate towards anode.

17. (i) Name the disease caused by deficiency of vitamin D.

(ii) Why cannot vitamin C be stored in our body?

18. Define the terms hypervitaminosis and avitaminosis.

19. Explain what is meant by :

(i) a peptide linkage (ii) a glycosidic linkage?

20. Give the sources of vitamin A and E and name the deficiency diseases

resulting from lack of vitamin A and E in the diet.

21. What are the main functions of DNA and RNA in human body.

SA(II) TYPE QUESTIONS (3 - MARK QUESTIONS)

1. How are carbohydrate classified?

2. (i) Name four bases present in DNA.

(ii) Which of them is not present in RNA.

(iii) Give the structure of a nucleotide of DNA.

3. Differentiate between the following :

(i) secondary and tertiary structure of protein.

(ii) α-Helix and β-pleated sheet structure of protein.

(iii) fibrous and globular proteins.

                                                    

To find the Determination of Contents of Tooth Powder

JAWAHAR NAVODAYA VIDYALAY,SONIPAT(HR) Chemistry Investigatory Project

PROJECT REPORT

To find the Determination of Contents of Tooth Powder

Exam. Roll No. :

Class                 :

Name              :

CERTIFICATE

This is to certify that this bonafide project work in the subject of chemistry has been done by ______________   of class XII science in the academic year 2015-2016  and submitted to AISSCE practical examination conducted by CBSE at Embassy of India School Moscow  on _______________

TEACHER IN CHARGE               PRINCIPAL

INTERNAL EXAMINER           EXTERNAL EXAMINER

Aim : To find the Determination of Contents of Tooth Powder/To test the acid and basic radicals in the toothpowder

Theory:

Toothpowder is a powder used with hands or with a toothbrush to clean and maintain the aesthetics and health of teeth. Toothpowder is used to promote oral hygiene: it can aid in the removal of dental plaque and food from the teeth, aid in the elimination and/or masking of halitosis and deliver active ingredients such as fluoride or xylitol to prevent tooth and gum disease

While the exact formula of each brand of toothpaste is proprietary, most toothpowders contain the same basic ingredients. These include:

Fluoride: Perhaps the most important toothpowders ingredient is fluoride. Fluoride incorporates itself into tooth enamel making your teeth more resistant to acids produced by plaque bacteria, as well as acids found in fruit juices, soda (both regular and diet) and certain foods. In toothpowders, fluoride is found in the form of sodium monofluorophosphate, stannous fluoride, or sodium fluoride.

Abrasives: Abrasives give toothpowders its cleaning power. They remove stains and plaque, as well as polish teeth. Common abrasives include calcium phosphates, alumina, calcium carbonate, and silica. Toothpowders should be abrasive enough to remove plaque and stains, but not abrasive enough to damage tooth enamel. Damaged tooth enamel also causes yellowing as the thinned enamel reveals the yellowish dentin layer below. Over the years, manufacturers have been quietly reducing the abrasiveness of their toothpowders.

Preservatives: Preservatives prevent the growth of microorganisms in toothpowders and eliminate the need to refrigerate toothpowders. Common preservatives include sodium benzoate, methyl paraben, and ethyl paraben.

Flavoring Agents: These are added to improve the taste of toothpowders. You may have noticed that toothpowders have very strong flavoring.This is necessary to cover up the horrid taste of most detergents, especially SLS.

Sweeteners: Sweeteners also improve the taste of toothpowders. Most toothpowder sweeteners are artificial and contribute very little to cavity formation. Saccharin is a common toothpowder sweetener

TEST FOR ACID RADICAL:

Experiment	Observation	Inference
Dilute sulphuric acid test A small amount of salt was treated with 1-2 ml of dilute sulphuric acid.	Colourless and odourless gas.   Brisk effervescence and evolution of carbon   dioxide which turns lime water milky.	CO32 – may be  Present
[1] To the solution of the salt dilute HCl was added. [2] To the solution of the salt magnesium sulphate solution was added.	[1] Brisk effervescence and evolution of carbon       dioxide which turns lime water milky. [2] White precipitate was obtained.	CO3 2– confirmed

TEST FOR ACID RADICAL:

Experiment	Observation	Inference
Dilute sulphuric acid test A small amount of salt was treated with 1-2 ml of dilute sulphuric acid.	No Observation	CO32 – SO32 –  S2 –  NO 2–     are absent
Concentrated sulphuric acid test            A small amount of salt was treated with 1-2 ml of conc.sulphuric acid.	No Observation	Cl –  Br –  I –  NO3 – CH3COO –  are absent
Salt solution + conc.HNO3 , boiled. Then + Ammonium molybdate solution + boiled.	A canary yellow ppt. was obtained.	PO43– confirmed

TEST FOR BASIC RADICAL

Experiment	Observation	Inference
Test for ammonium (ZERO GROUP) A little of soda lime was added to the salt on a watch glass and rubbed with few drops of water.	No Gas evolved	NH4+ is absent.
To the salt solution dil. HCl was added.	No  ppt. was formed	Gr-I ( Pb2+) is absent.
To the filtrate of the above solution H2S gas was passed.	No  ppt. was formed	Gr-II ( Pb2+ ,Cu 2+, As 3+)  absent.
To the filtrate few drops of conc. HNO3 was added and H2S gas was boiled off and filtered. To the filtrate NH4Cl and NH4OH were added.	No  ppt. was formed	Gr-III ( Fe3+) absent
To the filtrate of the above solution H2S gas was passed.	No  ppt. was formed	Gr-IV(Mn2+,Zn2+,Ni2+,Co2+)Radicals absent

GROUP –V   ANALYSIS  {The ppt. of group-V was dissolved in hot dil. acetic acid and divided into three parts:}

Experiment	Observation	Inference
[1] First part + Ammonium oxalate solution	White ppt. was obtained	Ca2+ confirmed

RESULT: The given Salt contains  carbonate  (CO₃^{2 –})   &  Phospahte PO₄^3– as anion  & Calcium Ca²⁺as cation.

Conclusion:

Several of the ingredients in toothpastes are found by some environmentally damaging or hazardous to the personal health.

These ingredients include:

•Artificial flavoring 
• Artificial colors 
• Triclosan 
• Sodium bicarbonate (baking soda) 
• Detergents 
• Fluoride
• Preservatives such as Methylparaben and Ethylparaben-parabens 
• Pyrophosphate

Homemade tooth powders are made by mixing  3 parts baking soda (cleanser) thoroughly with 1 part salt (the abrasive). As a direct result of these concerns, some people have started making their own tooth paste instead, which -while still not completely ecologic due to the use of baking soda- still eliminates much environmentally or health damaging ingredients. Also, commercial toothpowders are made which are less or even non-environmentally damaging. Such preparations are made from herbal resins, propolis and myrrh.

Class XII CHEMISTRY chapter 1, 2, 3 AND 4 PRACTICE PAPER

T

CLASS –XII   SUBJECT: CHEMISTRY (UT-1, 2, 3 AND 4)   PRACTICE PAPER

TIME: 3 hr  

MAXIMUM MARKS: 70

NOTE: All questions are compulsory

MCQs Section A

Q1 The value of van’t Hoff factor for ethanoic acid in benzene is (a) 1.0 (b) 1.5 (c) 0.5 (d) 2

 Q2 Which of the following aqueous solutions should have the highest boiling point? (a) 1.0 M NaOH (b)      1.0 M Na2SO4 (c) 1.0 M NH4NO3 (d) 1.0 M KNO3

Q3 In comparison to a 0.01 M solution of glucose, the depression in freezing point of a 0.01 M MgCl2      solution is _____________.(a) the same (b) about twice (c) about three times (d) about six times

Q4 If we place the blood cells in a solution containing less than 0.9% (m/V) sodium chloride. They would     swell. This is because (a) the solution is hypotonic (b) the solution is isotonic (c) the solution is      hypertonic (d) none of these

Q5 The positive value of the standard electrode potential of Cu2+/Cu indicates that ______________.  (a) this redox couple is a stronger reducing agent than the H+ /H2 couple. (b) this redox couple is a stronger oxidising agent than H+ /H2. (c) Cu can displace H2 from acid. (d) Cu cannot displace H2 from acid

Q6 On increasing temperature, (a) ionic conductance increases and electronic conductance decreases. (b) ionic conductance decreases and electronic conductance increases. (c) both ionic and electronic       conductance increase. (d) both ionic and electronic conductance decrease

Q7 Charge carried by 1 mole of electrons is    (a) 6.023 × 1023 coulomb (b) 9.65 × 104 coulomb (c) 1.6 ×       10–19 coulomb  (d) 6.28 × 1019 coulomb

Q8 Which of the following is a zero order reaction? (a) Decomposition of N2O5 (b) Decomposition of     NH3 (c) Decomposition of N2O (d) Radioactive decay of unstable nuclei

Q9 The half life of a first order reaction is 69.35 sec.      The value of rate constant of the reaction is (a)       1.0 s–1 (b) 0.1 s–1 (c) 0.01 s–1 (d) 0.001 s–1

Q10 The magnetic moment is associated with its spin angular momentum and orbital         momentum.        Spin only magnetic moment value of Cr3+ ion is ____________. (a) 2.87 B.M. (b) 3.87 B.M. (c) 3.47         B.M. (d) 3.57 B.M.

Q11 Transition elements show magnetic moment due to spin and orbital motion of electrons. Which of        the following metallic ions have almost same spin only magnetic moment?  (a)       Co2+    (b) Cr2+          (c) Mn2+ (d) Cr3+

Q12 The electronic configuration of Cu(II) is 3d 9 whereas that of Cu(I) is 3d10. Which of the following is correct? (a) Cu(II) is more stable (b) Cu(II) is less stable (c) Cu(I) and Cu(II) are equally stable (d) Stability of Cu(I) and Cu(II) depends on nature of copper salt

Assertion-Reason Questions In the following questions, two statements are given—one labeled Assertion (A) and the other labeled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

(a) Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of the Assertion (A).

(b) Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).

(c) Assertion (A) is correct, but Reason (R) is incorrect statement.

 (d) Assertion (A) is incorrect, but Reason (R) is correct statement

Q13 Assertion (A) : Zn, Cd and Hg cannot be regarded as transition elements. .

       Reason (R) : These  elements do not belong to the d-block of the periodic table.

Q14 Assertion (A) : Rusting of iron is quicker in saline water than in ordinary water.

         Reason (R) : Salt water helps in flow of current in the miniature cell developed on the iron surface.

Q15 Assertion (A) : Order of the reaction can be zero or fractional.

        Reason (R) : We cannot determine  order from balanced chemical equation.

Q16 Assertion (A) : The solubility of a gas in a liquid increases with increase of pressure.

         Reason (R) : The solubility of a gas in a liquid is directly proportional to the pressure of the gas.

EACH QUESTION CARRY 2 MARKS  (12) SECTION B

Q17 Define Molecularity of a Reaction  and pseudo order reaction  with examples

Q18  Units of Zero order reaction and first order of reaction

Q19 A solution of Ni(NO3)2 is electrolysed between platinum electrodes using  a current of 5 amperes for 20 minutes. What mass of Ni is deposited at the cathode?

Q20  Discuss the  Variation of Conductivity and Molar Conductivity with Concentration

Q21.  State Henry’s law and mention some important applications?

Q22 Based on solute-solvent interactions, arrange the following in order of increasing solubility in n-octane and explain. Cyclohexane, KCl, CH3OH, CH3CN.

EACH QUESTION CARRY3 MARKS (18) SECTION C

Q23 What is meant by positive and negative deviations from Raoult's law and how is the sign of ΔmixH related to positive and negative deviations from Raoult's law.

Q24 The vapour pressure of pure liquids A and B are 450 and 700 mm Hg respectively, at 350  K . Find out the composition of the liquid mixture if total vapour pressure is 600 mm Hg. Also find the composition of the vapour phase.

Q25 Describe the preparation of potassium dichromate from iron chromite ore. What is the effect of increasing pH on a solution of potassium dichromate? Or

How does the acidified permanganate solution react with (i) iron(II) ions (ii) SO2and (iii) oxalic acid? Write the ionic equations for the reactions.

Q26 Give examples and suggest reasons for the following features of the transition metal chemistry:

(i)The lowest oxide of transition metal is basic, the highest is amphoteric/acidic.

(ii)A transition metal exhibits highest oxidation state in oxides and fluorides.

(iii) The highest oxidation state is exhibited in oxoanions of a metal.

Q27 (i) State two advantages of H2—O2 fuel cell over ordinary cell

(ii) What type of a battery is lead storage battery? Write the anode and cathode reactions and the overall cell reaction occurring in the operation of a lead storage battery

Q28 i) Calculate ∆r G° for the reaction        Mg(s) + Cu2+(aq)                 Mg2+(aq) + Cu(s) Given: Eo cell = +2.71 V, 1 F = 95600 C mol–1 (ii) Name the type of cell which was used in Apollo space programme for providing electrical power.

EACH QUESTION CARRY 4 MARKS (9)  SECTION D

Q29 The d-block elements are those elements in which the last electron enters the d-subshell of the penultimate shell. The general electronic configuration of these elements is (n – 1) d1–10 ns 1–2, where n is outermost shell. The d-block consisting of groups 3–12 occupies the large middle section of the periodic table. The elements of d-block are also known as transition elements as they possess properties that are transitional between the s and p block elements. A transition element is defined as an element which has incompletely filled d-orbitals in its ground state or any one of its oxidation states. There are four series of transition elements spread between group 3 and 12. First transition series or 3d-series: Scandium (21Sc) to Zinc (30Zn), Second transition series or 4d-series: Yttrium (39Y) to Cadmium (48Cd), Third transition series or 5d-series: Lanthanum (57La) and Hafnium (72Hf) to Mercury (80Hg) (Omitting 58Ce to 71Lu), Fourth transition series or 6d-series: Begins with Actinium (89Ac) is still incomplete.

In what way is the electronic configuration of transition elements different from that of the nontransition elements?

2. Why is zinc not regarded as a transition clement?

3. Why does a transition series contain 10 elements?

4. Name the element which shows outer electronic configuration 3d3 4s 2

5. What are interstitial compounds?

Q30 A solution which obeys Raoult’s law strictly is called an ideal solution, while a solution which shows deviations from Raoult’s law is called a non-ideal solution or real solution. Suppose the molecules of the solvent and solute are represented by A and B respectively, and let gAB, gAA and gBB are the attractive forces between A—B, A—A and B—B respectively. An ideal solution of the components A and B is defined as the solution in which the intermolecular interactions between the components A—B are of the same magnitude as the intermolecular interactions found in the pure components A—A and B—B. Similarly,a non- ideal solution of the components A and B is defined as the solution in which the intermolecular interactions between the components A—B are of the different magnitude as the intermolecular interactions found in the pure components A—A and B—B.

 1. What type of liquids form the ideal solution?

2. Give one example of an ideal solution.

 3. Write two characteristics of non-ideal solution

4. On mixing liquid A and liquid B, volume of the resulting solution decreases, what type of deviation from Raoult’s law is shown by?

EACH QUESTION CARRY 5 MARKS (15) SECTION E

Q31 (i) Define the following terms: (a) Azeotrope (b) Osmotic pressure (c) Colligative properties (ii) Calculate the molarity of 9.8% (w/w) solution of H2SO4 if the density of the solution is 1.02 g mL–1. (Molar mass of H2SO4 = 98 g mol–1)

Q32 i) State Kohlrausch law of independent migration of ions. Write an expression for the molar conductivity of acetic acid at infinite dilution according to Kohlrausch law. (ii) Calculate  for acetic acid. Given that   (HCl) = 426 S cm2 mol–1,  (NaCl) = 126 S cm2 mol–1   (CH3COONa) = 91 S cm2 mol–1

Q33 (i)The rate constant for a first order reaction is 60 s –1. How much time will it take to reduce the initial concentration of the reactant to its 1/16th value?

(ii) A reaction is first order in A and second order in B. (i) Write the differential rate equation. (ii) How is the rate affected on increasing the concentration of B three times? (iii) How is the rate affected when concentration of both A and B are doubled?

Important question of amines and diazonium salt

SUBJECT – CHEMISTRY THEORY (043) 2022-23

CHAPTER- AMINES

MM: 70                                                                            

TIME : 3 HOURS

General instructions: 

Read the following instructions carefully.

a) There are 35 questions in this question paper with internal choice.

b) Section A consist of 18 multiple-choice questions carrying 1 mark each.

c) Section B consists of 7 very short answer questions carrying 2 marks each.

d) Section C consists of 5 short answer questions carrying 3 marks each.

e) Section D consists of 2 case based questions carrying 4 marks each.

f) Section E consist of 3 long answer questions carrying 5 marks each.

g) All questions are compulsory.

h) Use of log tables and calculators is not allowed.

Section- A

The following questions are multiple choice questions with one correct answer each question carries one mark there is no internal choice in this section.

 

1. When a haloalkane is heated with KCN in aqueous ethanoic solution, the product formed is-

a) Alkyl nitrite                                                 

b) nitro alkane 

     c)  alkane nitrile                                                    

      d) carbylamine      

2. Amine that cannot be prepared by Gabriel phthalimide synthesis is-

a) Aniline                                                           

b)  benzyl amine 

     c) tertiary-butylamine 

     d) isobutylamine

3. Which of the following amine has highest boiling point?

a) Pentaamine  

b) 2-methylbutanamine

c) 2,2-dimethylpropamine

d) 3-methylbutamine              

4. The amine that reacts with NaNO2 and HCl to give yellow oily liquid is-

a) Ethylamine.    

b) Diethylamine

c) Isopropyl amine

d) Secondary butylamine    

5. Sandmeyer reaction of diazonium salt is a replacement of N2by-

a) Halogen Cl or Br

b) Hydroxyl group

c) Coupling

d) Hydrogen        

6. One of the following amines will not undergo Hoffmannbromamide reaction-

a) CH3CONHCH3

b) CH3CH2CONH2

c) CH3CONH2

d) C6H5CONH2   

7. The correct order of the basic strength of methyl substituted amines in aqueous solution is

a) CH3NH2 > (CH3)2NH > (CH3)3N

b) (CH3)2NH > CH3NH2 >  (CH3)3N

c) (CH3)3N >CH3NH2 > (CH3)2NH

d) (CH3)3N > (CH3)2NH > CH3NH2

8. The correct statement regarding the basicity of arylamine is

a) arylamines are generally more basic than alkylamines because of aryl group

b) arylamines are generally more basic than alkylamines because the nitrogen atom in aryalamines is sp- hybridised

c) arylamines are generally less basic than alkylamines because the nitrogen lone- pair electrons are delocalised by intraction with the aromatic ring π- electron system

d) arylamines are generally more basic than alkylamines because the nitrogen loan-pair electrons are not delocalisedby interaction with the aromatic ring π-electron system.            

9. What reagent is used in Hinsberg test of amines?

a) (CH3CO)2O and pyridine

b) C6H5SO2Cl followed by aq. NaOH

c) NaNO2 in aq. H2SO4

d) CH3I(excess) followed by AgOH  

10. Aniline reacts with sodium nitrite and hydrochloric acid at 273 -278 K to give:

a) Benzene

b) Benzene diazonium chloride

c) Chlorobenzene

d) o-chloroaniline    

11. Propane amide on reaction with bromine in aqueous NaOH gives:

a) Propanamine

b) ethanamine

c) N-Methyl ethanamine

d) Propanenitrile               

12. The gas evolved when methylamine reacts with nitrous acid is:

a) NH3

b) N2

c) H2

d) C2H6     

13. Which of the following is not correct regarding aniline?

a) It is less basic than ethyl amine

b) It can be steam distillated

c) It reacts with sodium to give hydrogen

d) It is soluble in water        

 

14. Acetamide and ethylamine can be distinguished by reacting with:

a) Aq. HCl and heat

b) Aq. NaOH and heat

c) Acidified KMnO4

d) Bromine water          

15. Given below are two statements labelled assertion (A) and reason(R).

Assertion(A)- Hinsberg's reagent can be used to distinguish primary amines from secondary amines.

Reason(R)- Benzenesulphonyl chloride is called Hinsberg'sreagent.

Select the most appropriate answer from the option given below :

a. Both A and R are true and R is the correct explanation of A.

b. Both A and R are true but R is not the correct explanation of A.

c. A is true but R is false.

d. A is false but R is true.             

16. Given below are two statements labelled assertion (A) and reason(R).

Assertion(A)- Solubility of amines in water decreases with increase in molar mass.

Reason(R)- Intermolecular H bonds formed by the higher amines are weaker.

Select the most appropriate answer from the option given below :

a. Both A and R are true and R is the correct explanation of A

b. Both A and R are true but R is not the correct explanation of A.

c. A is true but R is false.

d. A is false but R is true.             

17. Given below are two statements labelled assertion (A) and reason(R).

Assertion(A)- Amines behave as a Lewis base.

Reason(R)- Amines have an unshared pair of electrons on nitrogen atom.

Select the most appropriate answer from the option given below :

a. Both A and R are true and R is the correct explanation of A.

b. Both A and R are true but R is not the correct explanation of A.

c. A is true but R is false.

d. A is false but R is true.          

18. Given below are two statements labelled assertion (A) and reason(R).

Assertion(A)- Acylation of amines gives a mono substituted product whereas alkylation of amines gives poly substituted product.

Reason(R)- Acyl group sterically hinders the approach of further acyl groups.

Select the most appropriate answer from the option given below :

a. Both A and R are true and R is the correct explanation of A.

b. Both A and R are true but R is not the correct explanation of A.

c. A is true but R is false.

d. A is false but R is true.         

 

 

 

 

Section - B

This section contains 7 questions with internal choice in two questions. The following questions are very short answer type and carry 2 marks each.

 

19. How will you distinguish between the following pairs of compounds:

        i) Aniline and ethanamine.

       ii) Aniline and N-methylaniline

20. Give reasons:

        i) Aniline does not undergo friedal Craft reaction.

       ii) (CH3)2NH is more basic than (CH3)3N in an aqueous solution.

OR

       i) Although -NH2 group is o/p directing in electrophilic substitution reactions, yet aniline, on nitration gives good yield of m-nitroaniline.

      ii) pKb of methylamine is less than that of aniline.

21. Write chemical equations for the following conversion:

       i) nitrobenzene to benzenoic acid

       ii) aniline to benzyl alcohol

OR

        i) Write the reaction involved in the following: Diazotisation

       ii) Give reason:

            Aromatic diazonium salts are more stable than aliphatic diazonium salts.

22. Illustrate the following with an example of reaction in each case-

       i) Sandmeyer reaction

       ii) coupling reaction

23. Complete the following reactions:

       i) CH3CH2NH2 + CHCl3+alc.KOH------->

       ii) CH3NH2+ C6H5COCl---------->

24. Ammonolysis of alkyl halides is not a good method to prepare pure primary amines. Explain.

25. State and illustrate the following:

                    Gabriel phthalimide synthesis.

     

Section- C

Section contains 5 questions with internal choice in two questions the following questions are sort answer type and carry 3 marks each.

26.  a) Write the chemical reaction of methylamine with benzyl chloride and write the 

             IUPAC name of the product obtained.

       b) Arrange the following in the increasing order of their pkbvalues:

              C6H5NH2 , NH3 , C2H5NH2 ,(C2H5)2 NH

27. Write the structures of main products when aniline reacts with the following reagents:

          i) Br2 water.          

         ii) HCl

         iii) (CH3CO)2O/Pyridine

 

28. Write the structures of A, B and C in the following:

                                Br2/aq. KOH                      NaNO2+ConcHCl/0-5 0C                  KI/∆

      i) C6H5CONH2  ---------- ---------àA ------ ---------------à  B ------ ----à  C

                         KCN                         LiAlH4                             CHCl3+alcKOH

     II) CH3Cl ---- ----------à A ---- -----------à  B -------------------- ---à   C

 

29. Give reasons for any three of the following observations:

a. Aniline is acetylated before nitration reaction.

b. pKb of aniline is smaller than the m-nitro aniline.

c. Primary amine on treatment with benzene sulfonyl chloride forms a product which is soluble in NaOH, however secondary amine gives product which is insoluble in NaOH.

d. Aniline does not react with methyl chloride in the presence of anhydrous AlCl3 catalyst.

30. Write the structures of main products when benzenediazonium chloride reacts with 

      the following reagents.

a) CuCN

b) CH3CH2OH

c) KI

Section- D

The following questions are case based questions. Each question has an internal choice and carries 4(1+1+2) marks each. Read the passage carefully and answer the questions that follow.

 

31. Benzene ring in aniline is highly activated. This is due to the sharing of lone pair of nitrogen with the ring which results in increase in the electron density on the ring and hence facilitates the electrophilic attack. The substitution mainly takes place at Ortho and para positions because electron density is more at Ortho and para positions. On reaction with aqueous bromine all the ortho and para position get substituted resulting  in the formation of 2,4,6- tribromoaniline. To get a monobromocompound, the amino group is acetylated before bromination. After bromination, the bromoacetanilide is acid hydrolysed to give the desired halogenated amine.     

a) Why does -NH2 group facilitates electrophilic attack in aniline?

b) Explain why: in aniline, the substitution mainly takes place at Ortho and Para positions.

c) Show the conversion of benzene into aniline.

 

32. In amines the N atoms of the amino group are SP3hybridised. Amines readily lose its electron pair and act as a base. In aliphatic amines ,the alkyl group tends to increase the electron density on the nitrogen atom due to the +I effect. In aromatic amines, the basic strengths are influenced by the presence of an electron withdrawing group at the O-, m- and p- position in the ring.

a) Lower member of aliphatic amines are soluble in water .Why?

b) Out of (CH3)3N  and and (CH3)2NH which one is more basic in aqueous solution?

c) Which isomer of C3H9N which does not react with Hinsberg’s reagent.

 

 

Section- E

The following questions are long answer type and carry five marks each two questions have internal choice.

 

33. An organic compound A with molecular formula C7 H7NO reacts with Br2/aq. KOH to give compound 'B', which upon reaction with NaNO2 and HCl at 00 Celsius gives 'C'. Compound 'C' 

on heating with CH3CH2OH gives hydrocarbon 'D'.  compound 'B' on further reaction with Br2 water gives white precipitate of compound 'E'. Identify the compound A,B,C,D and 'E'.

Also justify your answer by giving relevant chemical equations.               

OR

An aromatic compound 'A' on treatment with aqueous ammonia and heating forms compound 'B' which on heating with Br2 and KOH forms a compound 'C' of molecular formula C6H7N. write the structure and IUPAC names of the compound A, B and C .Justify your answer by giving relevant chemical equations.          

34. i) Write the structure of main products when benzenediazonium chloride (C6H5N2+Cl-) reacts with the following reagents:

a) KI         b) C2H5OH

      ii) write the structures of A B and C in the following reactions:

                                                                     LiAlH4                                    HNO2 /Low temp

CH3Cl+ KCN (alc)----------------->A-- --------------------->B------------------------>C

                                                                           OR

     i) Write the reactions involved in the following:

a) Hoffmann’s Bromamide degradation reaction

b) Carbylamine reaction

35. i)    Convert the following:

a) Phenol to N-phenylethanamide

b) Chloroethane to methanamine

c) Propanenitrile to ethanal.

ii) What happens when-

a) N-ethylethaneamine reacts with benzenesulphonyl chloride.

b) Aniline reacts with chloroform in the presence of alcoholic potassium hydroxide.

 

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