CBSE Class 12 Chemistry Revision Worksheet

1.‘Stability of a crystal is reflected in the magnitude of its melting point’. Comment.

2.Why does LiCl acquire pink colour when heated in Li vapour?

3.Explain the following terms with a suitable example:

a) 12 – 16 compounds

b) Ferrimagnetism

4.Write equation for the following:

a) Finkelstein reaction

b) Sandmeyer reaction

5.A unit cell consists of a cube in which there are A atoms at the corners and B atoms at the face centres. Two A atoms are missing from the two corners of the unit cell. What is the formula of the compound?

6.An optically active halide of formula C₄H₉Br undergoes substitution by OH^─ with an inversion of configuration. Explain the mechanism involved in the reaction.

7.a) Distinguish between the following pairs:

1- Chlorobutane and 1- Chlorobutene

b) Predict the order of reactivity of the following compounds in SN1 reactions:

C₆H₅CH₂Br, C₆H₅CH(C₆H₅)Br, C₆H₅CH(CH₃)Br, C₆H₅C(CH₃)(C₆H₅)Br

c) Write the IUPAC name of the following:

(CH₃)₃CCH₂CHBrC₆H₅

8.An element occurs in bcc structure. It has a cell edge length of 250 pm. Calculate the molar mass if its density is 8.0 g cm^-3.

9.How will you bring about the following conversions:

a) Propene to 1- Nitropropane

b) Benzyl alcohol to Benzyl cyanide

c) Chlorobenzene to p- nitrophenol

10.a) If KCl is doped with 10^-4 mole % of CdCl₂, what is the concentration of cation vacancy? b) A compound forms a hexagonal closed packed structure. What is the total number of voids in 0.5 mol of it?

11.a) What are enantiomers? b) Explain why?

i) Grignard reagent should be prepared under anhydrous conditions.

ii) Tertiary halides do not undergo S_N2 mechanism.

1. Name the non-stoichiometric point defect responsible for colour in alkali halides?

2. What type of alignment in crystals makes them ferrimagnetic?

3. Write equation for the following reactions;

a) Wurtz – Fittig reaction

b) Friedel – Crafts acylation of Chlorobenzene

4. Explain the following terms:

a) Ferromagnetism

b) Tetrahedral void

5. A metallic oxide crystallizes in a hexagonal closed packed array of oxide ions with two out of every three octahedral voids occupied by the metal ions. Derive the formula of the metallic oxide.

6. An optically active compound having molecular formula C6H13Br reacts with aq.KOH to give a racemic mixture of products. Write the mechanism involved in the reaction.

7. a) Give a chemical test to distinguish between the following pairs of compounds:

Phenyl chloride and Benzyl chloride

b) Arrange the following compounds in the increasing order of the reactivity towards the reaction with caustic alkali:

Chlorobenzene, 4-chloro-1-methyl-benzene, 4- nitrochlorobenzene and 2,4,6-trinitrochlorobenzene

c) Write the IUPAC name of the following compound:

p- ClC₆H₄CH₂CH(CH₃)₂

8. Copper crystallizes into an fcc lattice with edge length 3.61 x 10^-8cm. Calculate the density of copper. [Given Cu = 63.5g mol^-1]

9. a) Identify the chiral molecule in the following:

Pentan -2-ol or Pentan-3-ol

b) Give reason:

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

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

10. How will you bring about the following conversions:

a) 1- Bromopropane to 2,3- dimethylbutane

b) Ethanol to propanenitrile

c) tert-Butyl bromide to isobutylbromide

11. A sample of ferrous oxide has actual formula Fe_0.93O_1.00. In this sample what fraction of metal ions are Fe²⁺ ions? What type of non-stoichiometric defect is present in this sample?

1.What type of semiconductor is obtained when silicon is doped with arsenic?

2.How are cation vacancies created in KCl crystal?

3.Write equation for the following:

a) Swarts reaction

b) Friedel Crafts nitration of Chlorobenzene

4.Explain the following terms:

a) Crystal lattice

b) Interstitials

5.Distinguish between orthorhombic and triclinic unit cells on the basis of :

a) Crystal parameters

b) Bravais lattices

6.a) Give a chemical test to distinguish between the following pairs:

1- Chloropropene and 3-Chloropropene

b) Which compound of the following pairs will react in S_N2 reaction with OH-

(CH₃)₃CCl or CH₃Cl

c) Write the IUPAC name of the following compound:

CH₃CH(p-ClC₆H₄)CH(Br)CH₃

7.Determine the type of cubic lattice to which a given crystal belongs if it has edge length of 290 pm and density is 7.80g cm^-3. (Molecular mass = 56g mol^-1 )

8.How will you bring about the following conversions:

a) Benzene to p-nitrochlorobenzene

b) Propene to 1-Propanol

c) 2-Bromopropane to Hexane

9. Analysis shows that nickel oxide has formula Ni_0.98O_1.00. What fraction of nickel exists as Ni²⁺ and Ni³⁺ ions?

10.a) Define racemization.

b) Give reason:

i) Vinyl chloride is unreactive in nucleophilic substitution reactions.

ii) P-Dichlorobenzene has higher melting point than those of o- and m- isomers.

1. Halogens are strong oxidising agents.Why?

2. What is F-centre?

3. Why is p-nitrophenol more acidic than p-cresol ?

4. Arrange the following compounds in the order of their increasing boiling point . Pental-1-ol,butan-1-ol,butan-2-ol,ethanol,propan-1-ol,methanol

5. What are azeotropes ?

6. How will you convert benzene to diphenyl?

7.Chloroform is stored in dark coloured bottles completely filled.Why?

8. Why is sulphuric acid not used during the reaction of alcohol with KI ?

9. Distinguish between order and molecularity.

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

11. The rate constant for the first order decomposition of H₂O₂ is given by the following equation.
log k = 14.34 -1.25 x 104 K/T
Calculate Ea for this reaction.

12. Write balanced equations for the following.
(a). NaCl is heated with H₂SO₄ in presence of MnO₂ .
(b). Thermal decomposition of barium azide.

13. In a closed packed structure of oxides, one-eighth of the tetrahedral holes are occupied by bivalent cations and half of the octahedral holes are occupied by trivalent cations. Find the molecular formula of the oxide.

14. For the decomposition of azoisopropane to hexane and nitrogen (first order)at 543 K ,the following data are obtained.
t (sec)           P(mm of Hg)
0                       35.0
360                   54.0
Calculate the rate constant.

15. State Henry’s law and mention some important applications.

16. (a) Write the mechanism of hydration of ethene to yield ethanol
(b) Write the reaction of Williamsons synthesis of 2-ethoxy-3methyl pentane starting from ethanol and 3-methyl pentan-2-ol

17. What are essential and non essential amino acids?

18. How is SO₂ an air pollutant ?How is its presence detected?

19. Write the reaction of copper metal with dilute and concentrated HNO₃.

20. Differentiate between globular and fibrous proteins.

21. a. How do you prepare phenol from (i) aniline (ii) cumene
b. Explain Reimer-Tiemann reaction with an example.

22. Give reason for the following
(a). Flourine is a stronger oxiding agent than chlorine......
(b). Nitrogen is less reactive at room temperature.
(c). Pentahalides are more covalent than trihalides.

23. An aqueous solution of 2% non volatile solute exerts a pressure of 1.004 bar at the normal boiling point of the solvent .What is the molar mass of the solute?

Q.1 How the following conversations can be carried out?

(i) Propene to propan‐1‐ol

(ii) Ethanol to but‐2‐yne

(iii) Toluene to benzyl alcohol

(iv) Benzene to 4‐bromonitrobenzene

(v) Benzyl alcohol to 2‐phenylethanoic acid

(vi) Ethanol to propanenitrile

(vii) 2‐Chlorobutane to 3, 4‐dimethylhexane

(viii) 2‐Methyl‐1‐propene to 2‐chloro‐2‐methylpropane

(ix) Ethyl chloride to propanoic acid

(x) But‐1‐ene to n‐butyl iodide

(xi) 2‐chloropropane to 1‐propanol

(xii) Isopropyl alcohol to iodoform

(xiii) Chlorobenzene to p‐nitro phenol

(xiv) 2‐Bromopropane to 1‐bromopropane

(xv) Tert‐Butyl bromide to isobutyl bromide

Q2. Account for the following:
(a) Chloromethane reacts with KCN to form ethanitrile as main product and with AgCN to form methyl isocyanide as chief product.
(b) Use of DDT was banned in United States in 1973.
(c) Benzylic halides show high reactivity towards SN¹ reaction.

Q4 Although chlorine is an electron‐withdrawing group, yet it is ortho‐, para‐directing in electrophilic aromatic substitution reactions. Why?

Q5. Why is sulphuric acid not used during the reaction of alcohols with KI?

Q6. Which of the following has the highest dipole moment? (i) CH₂Cl₂ (ii) CHCl₃ (iii) CCl₄

Q7 What are ambident nucleophiles? Explain with an example.

Q8. Explain why (i) the dipole moment chlorobenzene is lower than that of cyclohexile chloride? (ii) Alkyl halides, though polar, are immiscible with water? (iii) Grignard reagents should be prepared under anhydrous conditions?

Q9. Give the uses of Freon‐12, DDT, carbon tetrachloride and iodoform.

Q10.Why iodoform has appreciable antiseptic property?

Q11.How many alkenes are possible with molecular formula C₂H₄Cl₂ ?

Q12.Gasoline is a mixture of
a. Hydrocarbons
b. Alcohols
c. Carbohydrates
d. Hydrocarbons and alcohols

Q13.auto oxidation of chloroform in air and sunlight produces a poisnous gas known as
a).chloropicrin
b) mustard gas
c).lewisite
d). phosgene

Q14.An aromatic compound ‘X’ (C₈H₈Br₂) on treatment with aqueous KOH gives ‘Y’(C₈H₉BrO).On Heating’X’ with alcoholic KOH ‘Z’ ( C₈H₇Br) is formed . The compound ‘Z’ on reacting with Br₂/CCl₄ forms ‘A’. The compound ‘A’reacts with fused KOH to give ‘B’.Write the chemical equations involved and identify all of them.

Q15 Explain the phenomenon of optical isomerism with the help of suitable examples.

Q1. How will you convert the following:

a) Benzene to diphenyl

b) Isopropyl chloride to n-propylbromide

c) Acetylene to propyne

d) Methyl bromide to acetic acid

e) Chlorobenzene to p-nitrophenol

Q2. What happens when:

a) Ethylbromide is reacted with AgCN.

b) Chloroform reacts with aniline in the presence of alcoholic KOH.

c) Benzene diazoniumchloride reacts with HCl in the presence of Cu powder.

Q3. Distinguish between:

a) Chlorobenzene and benzyl chloride

b) Ethyl alcohol and propyl alcohol

c) Bromoethane and Chloroethane

Q4. With alcoholic potash compound A (C₃H₇Br) gives B(C₃H₆). On oxidation B gives acetic acid, CO₂ and water. With HBr, it gives D, an isomer of A. Identify compounds A to D.

Q5. Explain why

a) Chlorine although electron withdrawing, yet is o- and p- directing in electrophilic aromatic substitution reactions.

b) 2-Bromobutane is chiral whereas Bromobutane is achiral.

Q6. Give the IUPAC names of the following compounds:

a) CHF₂CBrClF

b) (CH₃)₂C = CHCH₂Br

c) CH₃C(p-Cl-C₆H₄)₂CH(Br)CH₃

Q7. Write all the possible structures for the molecular formula C₅H₁₁Br. Give their IUPAC names and classify the isomers as 1^o, 2^o or 3^o. Which of these are optically active?

Q8. Predict the order of reactivity of four isomeric iodobutane in S_N1 and S_N2 reactions.

Q9. Haloalkanes undergo nucleophilic substitution reactions while haloarenes undergoes electrophilic substitution reactions. Explain.

Q10. The treatment of alkyl chlorides with aqueous KOH leads to the formation of alcohols but in the presence of alcoholic KOH, alkenes are major products.Why?

Q1. Use a Grignard’s reagent to prepare the following alcohols from butan-2-one;

a) 3-Methyl pentan-3-ol

b) 2-Phenyl pentan- 2-ol

Q2. Give the following reactions;

a) Kolbe’s reaction

b) Friedal Craft acylation

c) Fries rearrangement

d) Reimer Tiemann reaction

Q3. Give reasons for the following;

a) Why ethers are relatively inert compounds.

b) Ortho and para nitrophenols are more acidic than Phenols.

c) Why is the b.p. of glycol high.

Q4. Give a chemical test to distinguish between;

a) propan-2-ol and benzyl alcohol

b) Butan-1-ol and butan-2-ol

Q5. Write reaction for the preparation of phenol from cumene.

Q6. Describe the mechanism of the formation of diethyl ether from ethanol in the prescence of conc. H₂SO₄.

Q7. Out of o-Nitrophenol and p-Nitrophenol which steam volatile and why?

Q8. How will you convert;

a) Benzene to Phenol

b) Phenol to Benzoic acid

c) Aniline to Iodobenzene

Q9. How are ethers prepared by Williamson’s synthesis? What are limitations for preparing unsymmetrical ethers in this method?

Q10.What happens when;

a) Butanol is heated with SOCl₂.

b) Methoxy propane is treated with HBr.

c) Anisole is reacted with HI at 373K.

Q11. Explain Hydroboration oxidation of alkene

1. Write the formulae and commercial names of the ores of the following metals:
a) Mercury
b) Zinc
c) Copper

2. Explain the following terms:
a) Bends
b) Ferromagnetic substances
c) Peptization
d) Autoreduction
e) Zeta potential
f) Ambidient nucleophile

3. Write the balanced chemical equation(s)to show that rusting of iron is envisaged as an electrochemical process.

4. Differentiate between :
a) Macromolecular and Multimolecular colloids.
b) Roasting and Calcination.
c) Ideal and Non –ideal solutions.
d) P-type and n-type semiconductors.

5. A first order reaction takes 40 minutes for 30% decomposition. Calculate its half life period.

6. Describe the metallurgical process of extraction of Aluminium from its ore.

7. Elaborate and explain:
a) Mond’s process
b) Fuel cells
c) Reverse osmosis
d) Pseudo –unimolecular reactions
e) Metal deficient defects.
f) Ultra filtration

8. Calculate the cell potential of the given cell;
Mg/Mg²⁺⁽0.01M) // Cu²⁺ (0.001M)/Cu .
Given ; E⁰(cell) = 3.05V

9. The rate of reaction quadruples when the temperature changes from 293K to 313K. Calculate the energy of activation of the reaction assuming that it does not change with temperature.

10. A solution of an aqueous CuSO₄ is electrolysed between platinum electrodes using a current of 5 Amperes for 20 minutes. What is the mass of product formed at cathode? Write the reaction taking place at cathode .

11. A 5% solution (by mass) of cane sugar in water has freezing point of 271 K. Calculate the freezing point of a 5% glucose in water if freezing point of pure water is 273.15K.

12. Convert the following:
a) Acetaldehyde to Acetamide.
b) Benzene to phenol
c) Benzoic acid to aniline
d) Benzyl alcohol to phenyl ethanoic acid.
e) Aniline to p-nitro aniline
f) But-1-ene to But-2-ene

13. Write the mechanism of acid catalysed dehydration of alcohols.

14. Write the mechanism of heterogenous catalysis.

15. Explain giving Chemical equation:
a) Rosenmund’s reduction
b) Clemmenson’s reduction
c) Aldol Condensation
d) Finkelstein reaction
e) Kolbe’s reaction
f) Wurtz reaction

16. Give reasons for the following
a) During nucleophilic addition reaction of carbonyls with ammonia derivatives pH is maintained between 3 to 4.
b) Benzene sulphanillic acid has high solubility in water.
c) Allylic halides have greater reactivity for SN¹ mechanism
d) Chloroform is stored under dark colour bottles
e) T- butyl ether is prepared using williamson’s synthesis as a special case
f) Aniline does not undergo friedel-craft reaction

17. Complete the following and write the IUPAC name of the major product formed
a) CH₃CH₂CH₂OCH₃ + HI -----------→
b) CH₃CH₂COOH + C₆H₅OH -----------→
c) C₆H₅NH₂ + HNO₂ + HCl ---------------→
d) CH₃CH=CH₂ + H₂O ----------------H+→

18. Distinguish between:
a) Phenol and ethanol
b) Acetaldehyde and benzaldehyde
c) Aniline and N- methyl aniline
d) Propanone and propanal

19. Write two uses of;
a) Carbon tetra Chloride
b) Ethanol
c) Methanal

20. What are alloys? Write the constituents of following alloys and write two uses each :
a) Solder
b) Brass
c) Steel

1. Convert the following

1. aniline to N‐phenyl ethanamide.

2. Propane to 1- bromopropane.

3 . propanol to lodoform.

4 .ethene to ethanol.

5. phenol to phenylethonoate.

6. Ehanol to 2 propanol.

7. Propane to 2- propanone

8. Aniline to fluorobenzene.

9. 2-propanol to 2-propanone.

10. propanoic acid to 1-propanol

11. Acetophenone to benzoic acid.

2. Give the structure of : 5-Oxohexanoic acid

3. Give example for following name reaction:
i. Reimer-Tiemann reaction
ii. Kolbe’s reaction

4. Write the mechanism of nucleophillic addition reaction in aldehydes.

5. Give one chemical test to distinguish:
i. Acetaldehyde and Benzaldehyde
ii. Benzophenone and Acetophenone

6.. Give reason
(a) Aldehydes are more reactive than Ketones towards Nucleophillic addition reaction
(b) There are two NH2 group in semi carbazide however only one is involved in the formation of semi carbazones.
(c) 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 fast as it is formed.

7. Accomplish the following conversions:
(a) Nitrobenzene to phenol (b) Methanamine to Ethanamine

8. (1) Primary alkyl halide C4H9Br (a) reacted with alcoholic KOH to give compound (b).Compound (b) is reacted with HBr to give (c) which is an isomer of (a).When (a) is reacted with sodium metal it gives Compound (d),C₈H₁₈ which is different from the compound formed when n-butyl bromide is reacted with sodium .Give the structural formula of (a) and write the equations for all the reactions.
2) An organic compound ˜A with molecular formula C₅H₅O . It does not reduce toulene or Fehling reagent but forms a bisulphite compound. It also gives iodoform tests. Identify A

9. (a)An organic compound A with molecular formula C₅H₈O₂ is reduced to neopentane on treatment with Zn-Hg/HCI. A forms a dioxime with hydroxylamine and gives a positive iodoform test and toulene test. Identify the compound A and deduce its structure.
(b) 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 structures and IUPAC names of compounds A,B,C.
(c) Account the following:
o-nitrophenol has lower boiling point than p-nitrophenol

10. Write one chemical equation to exemplify the following reactions:
b) Carbylamine reaction
c) Hofmann bromamide reaction.

11.An organic compound with the molecular formula C₉H₁₀O forms 2,4-DNP derivative, reduces Toulene reagent and undergoes Cannizaro reaction. On vigorous oxidation, it gives 1,2-benzene dicarboxylic acid. Identify the compound.

12.Write the steps and conditions involved in the following conversions:
i) Acetophenone to 2-phenyl-2-butanol.
ii) Propene to acetone.

13.Why propanol has higher boiling point than that of the hydrocarbon, butane?

14.. Give the IUPAC name of the following compounds:CH₃COCH₂CH₂Cl, CH₃CH(OH)CH₂CHO

15.Write zwitter ion of amino acetic acid.

16.. Give reason:
i) It is difficult to prepare pure amines by ammonolysis of alkyl halide.
ii) Aniline is a weaker base than cyclohexylamine.
iii) Amines have lower boiling points than those of the corresponding alcohols

17.a) An organic compound ‘A’ C₈H₆ on treatment with dilute H₂SO₄ containing mercuric sulphate gives compound ‘B’. Which can also be obtained from a reaction of benzene with acid chloride in the presence of AlCl₃? ‘B’ on treatment with I2 in aq.KOH gives ‘C’ and yellow compound ‘D’. Identify A,B,C and D. Give the chemical reactions involved.
b) How will you convert:
i) acetaphenone to ethyl benzene ii) propanone to 2-Propanopl.

18.. Explain
(a) Why preparation of chloroalkane by the action of SOCl₂ On alcohol is preferred?
(b) Why is H₂SO₄ not used during the reaction of alcohol with KI.?
(c) Why p-isomer of dihalobenzene has M.P. 70 to 100 0 C

Higher than ortho and meta isomer?

19. (a) Give a chemical test to distinguish between CH₃CHO and CH₃COCH₃
(b) Convert:
(i) Benzaldehyde to benzoic acid
(ii) Benzoic acid to benzamide
(iii) 4- methyl acetophenone to benzenedicarboxylic acid
(a) Give a chemical test to distinguish CH₃COOH and C6H₅COOH
(b) Convert:
(i) Acetaldehyde into 2-propanol
(ii) Toluene into benzaldehyde
(iii) Ethane into But-2enal

20. Give reasons

1. Haloalkane undergo nucleophilic substitution reaction.

2. Alchohol act as a weak base.

3. Phenol exhibit acidic behaviour

4. Ether posses dipole moment even alkyl groups are identical.

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

6. Alcoxides are more reactive than ketones towards Nucleophilic reagents?

7. Boiling points of ether are lower than isomeric alcohols?

8. Acetic acid is weaker than chloroacetic acids?

9. During the prepration of ammonia derivatives of aldehydes &ketones . pH of the reaction is carefully controlled?

10. Presence of acetic anhydride is necessary in the oxidation of toulene to benzaldehydrade by chromic oxide?

11. Chloroacetic acids has higher pH value than acetic acid?

12. Electrophilic substitution reaction in benzoic acids takes place at meta position?

13. Alkyl amines are stronger base than Aryl amines?

14. Like ammonia amines are good nucleophilles?

15. In contrast to arenes aliphatic hydrocarbones do not undergo nitration easily?

16. What for quaternary ammonium salts are widely used?

17. Toluene is more readily nitrated than benzene?

18. Haloalkanes are more reactive then haloamines?

19. Unlike alcohols ,phenols cannot be easily protonated?

20. Alkyl nitrite have lower boiling point than the corresponding carboxylic acids?

21. Why do aldehyde / ketone behave like polar compounds?

22. Haloarenes are insoluble in water but soluble in benzene?

23. Formaldehyde gives cannizaro reaction whereas acetaldehyde not?

24. Carboxylic acid do not give the characteristic test of carboxylic group?.