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

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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?

CBSE CHEMISTRY SAMPLE Question Paper 2023-24 set- I

REASONING QUESTIONS ORGANIC CHEMISTRY

1.     Before nitration aniline is converted into acetanilide

2.     Aryl halides can not be prepared by the reaction of  phenol with hydrogen halides.

3.     Sulphuric acid is not used during the reaction of alcohols with KI.

4.     The haloalkanes are only very slightly soluble in water

5.     Haloalkanes react with KCN to form alkyl cyanides as main product while AgCN forms isocyanides as the chief product.

6.     Although chlorine is an electron withdrawing group, yet it is ortho-, para- directing in electrophilic aromatic substitution reactions.

7.     The dipole moment of chlorobenzene is lower than that of cyclohexyl chloride.

8.     Grignard reagents should be prepared under anhydrous conditions.

9.     p-dichlorobenzene has higher melting point than those of o- and m- isomers.

10.  COH bond angle in alcohols is slightly less than the tetrahedral angle.

11.  The C-O bond length in phenol is slightly less than that in methanol.

12.  Tertiary alcohols do not under go oxidation reaction.

13.  Ortho and para nitrophenols are more acidic than phenols.

14.  Bimolecular dehydration of alcohols is not appropriate for the preparation of ethyl methyl ether.

15.  Alkyl aryl ethers when react with HX yields phenol and alkyl halide not aryl halide and alcohol.

16.  Propanol has higher boiling point than that of the hydrocarbon, butane.

17.  o-nitro phenol is steam volatile while p-nitrophenol is not.18.  o-nitro phenol os more acidic than ortho methoxyphenol

19.  Boiling point of ethanol is higher than that of methoxymethane.

20.  Carboxylic acids are stronger acids than phenols.

21.  Aromatic carboxylic acids do not under go Friedel-Crafts reaction.

22.  Cyclohexanone forms cyanohydrin in good yield but 2,2,6-trimethylcyclohexanone does not.

23.  There are two –NH₂ groups in semicarbazide. However, only one is involved in the formation of semicarbazones.

24.  During the preparation of esters from a carboxylic acid and an alcohol in the presence of an acid catalyst, the water or the ester should be removed as soon as it is formed.

25.  Although phenoxide ion has more number of resonating structures than carboxylate ion, carboxylic acid is a stronger acid than phenol.

26.  Anline does not undergo Friedel-Crafts reaction.

27.  pK_b of aniline is more than that of methylamine.

28.  Ethylamine is soluble in water whereas aniline is not.

29.  Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide.

30.  Although amino group is o- and p- directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m-nitroaniline.

31.  Diazonium salts of aromatic amines are more stable than those of aliphatic amines.32.  Gabriel phthalimide synthesis is preferred for synthesizing primary amines.

33.  Aromatic primary amines cannot be synthesized by Gabriel phthalimide synthesis.

34.  Amines are les acidic than alcohols of comparable molecular masses.

35.  Primary amines have higher boiling point than tertiary amines.

36.  Aliphatic amines are stronger bases than aromatic amines.

37.  Aromatic  ammines are less basic than aliphatic ammines.

38.  Ammonolysis of alkyl halide does not give corresponding ammines in pure state.

39.  If NO₂ or COOH groups are attached to a carbon of benzene ring electrophilic substitution becomes difficult.

40.  Haloalkane undergo nucleophilic substitution reaction.

41.  Alcohol act as a weak base.

42.  Phenol exhibit acidic behavior.

43.  Ether possess dipole moment even alkyl groups are identical.

44.  Carboxylic acids have high boiling point than alcohols of comparable molecular mass.

45.  Aldehydes are more reactive than ketones towards Nucleophilic reagents.

46.  Boiling points of ether are lower than isomeric alcohols.

47.  Acetic acid is weaker than chloroacetic acids.

48.  Electrophilic substitution reaction in benzoic acids takes place at meta-position

49.  Alkyl ammines are stronger base than Aryl ammines

50.  Like ammonia ammines are good nucleophiles.

51.  Toluene is more readily nitrated than benzene

52.  Unlike alcohols ,phenols cannot be easily protonated.

53.  Why do aldehydre/ketone behave like polar compounds?

54.  Haloarenes are insoluble in water but soluble in benzene

55.  Formaldehyde gives cannizzaro reaction whereas acetaldehyde not

56.  Carboxylic acid do not give the characteristic test of carbonyl group

57.  Carbonyl compound shows nucleophillic addition reaction.

Important Distinguish between organic pairs

Class XII Chemistry Distinguish between organic pairs

Lucas test

• Used to distinguish primary, secondary and tertiary alcohols.

• Lucas reagent – equimolar mixture of conc. HCl and anhydrous ZnCl2

• Alcohol is treated with Lucas reagent, turbidity due to the formation of insoluble alkyl chloride is observed.

• If the turbidity appears immediately, the alcohol is tertiary.

• If the turbidity appears in about five minutes, the alcohol is secondary.

• A primary alcohol does not react with Lucas reagent at room temperature and hence no turbidity is formed.

Iodoform test

• Iodoform test is a test for the CH3-CO group and is characteristic for alcohols and methyl ketones

• Reagents- compounds containing CH3-CO or CH3-CH(OH) group, sodium hydroxide and iodine 

• Product formed- iodoform,(CHI3) which is a pale yellow in colour

Tollens’ test

• Given by aldehydes and formic acid.

• Tollen’s reagent- ammoniacal silver nitrate solution 

• The aldehydes are oxidised to corresponding carboxylate anion.The reaction occurs in alkaline medium.

• A bright silver mirror is produced due to the formation of silver metal.

• Also known as Silver mirror test.

Fehling’s test

• Fehling reagent comprises of two solutions,

• Fehling solution A and Fehling solution B

• Fehling solution A is aqueous copper sulphate 

• Fehling solution B is alkaline sodium potassium tartarate (Rochelle salt).

• On heating an aldehyde with Fehling’s reagent, a reddish brown precipitate is obtained

this test is not given by benzaldehyde

Azo dye test

• It involves the reaction of any aromatic primary amine with nitrous acid followed by treatment with an alkaline solution of 2-naphthol, when a brilliant yellow , orange or red coloured dye is obtained.

• Used to distinguish between aliphatic primary amine and aromatic primary amine.

Hinsberg’s test

• Used for distinguishing primary, secondary and tertiary amines.

• Hinsberg’s reagent- benzenesulphonyl chloride (C6H5SO2Cl)

• In this test amine is shaken with Hinsberg’s reagent in presence of excess of aqueous KOH solution.

• A primary amine gives a clear solution which on acidification gives an insoluble N-alkylbenzenesulphonamide.10

• A secondary amine gives an insoluble N,N-dialkylbenzenesulphonamide which remains unaffected on addition of acid.

• A tertiary amine does not react at all. Therefore, it remains insoluble in the alkaline solution but dissolves on acidification to give a clear solution.

Carbylamine test-

only Primary aliphatic and aromatic amines are treated with chloroform and KOH . they produce isocynide (RNC) compound having foul smells.

Sodium bicarbonate test-

Carboxylic acids react with NaHCO3 with Brisk effeverscene and librates CO2 gas passed lime water becomes milky due to formation of calcium carbonates.futher more passed through it. its milkiness disappears due to formation of calcium bicarbonate 

while phenol being acidic it does not give this test because phenol is weak acid than carboxylic acids(carboxylic acids having most stable resonating structures)

Ferric chloride tests FeCl3.- phenol reacts with FeCl3 ,forms purple/violet coloured complex 

The given organic samples are teated with ferric chlorides If the sample turns to red, green, purple, or blue colouration then it indicates the presence of phenols and its derivatives.

Ferric chloride will not react with any aliphatic alcohol

Differentiate 

1. Phenol and benzoic acid

2. Butan-1-ol and 2-methylpropan-2ol

3. CH3CH2NH2 and(CH3)2NH

4. Ethyl amine and diethyl amine

5. Propan-1-ol and propan-2-ol

6. Methyl ethanoate and ethyl ethanoate

7. Aniline and N-ethyl aniline

8.  N methyl propane-2 amine and N -ethyl-N methyl ethanmine

9. Aniline and benzylamine

10. Ethylamine and Aniline

To analyse the given sample of salt for detection of one acidic and one basic radical

Aim: - To analyse the given sample of salt for detection of one acidic and one basic radical

Observation table-

A) Detection of acidic  radical(anion)

S.N.	EXPERIMENT	OBSERVATION	INFERENCE
1	Salt + Dil. H2SO4 and warm solution	Colourless gas with vinegar like smell evolves	Acetate (CH3COO-) may be present
2.	Confirmatory test for Acetate: (a)  Oxalic acid test: take 1 g of salt in test tube and add small amount of oxalic acid + one -two drops of distilled water   (b)  Ferric Chloride test: take 1 g of salt in test tube and add 1-2 ml distilled water , shake well and add 1-2 ml of neutral ferric chloride solution to it	Smell of vinegar obtained       Deep red color appears	Acetate (CH3COO-) is confirmed       Acetate (CH3COO-) is confirmed

 

Detection of basic radical(cation)

S.N.	EXPERIMENT	OBSERVATION	INFERENCE
1	Salt + NaOH solution + heat	No gas evolve	Zero group is absent
2.	Prepare original solution of salt by dissolving in 20 ml of water	Cleat solution is formed	Water soluble salt is present
3.	Small amount of OS + Dil. HCl solution	White precipitate is formed	Group -I is present Pb2+ may be present
4.	Confirmatory test of Pb2+: dissolve the precipitate in hot water and divide it into three parts (a)  part -1 + KI solution (b)  part-2 + potassium chromate   (c)  part-3 + few drops of alcohol + dil. H2SO4	Yellow precipitate  yellow precipitate is obtained which is soluble in NaOH  White precipitate is obtained which is soluble in ammonium acetate	Pb2+ is confirmed  Pb2+is confirmed   Pb2+ is confirmed

Result: in given sample of salt on acidic radical acetate (CH3COO^-) and one basic radical lead (Pb²⁺) is present.