12th chemistry Important Question Bank Unit wise

 GOVERNMENT HIGHER SECONDARY SCHOOL-KEERIPATTY

 XII- CHEMISTRY – QUESTION BANK

 UNIT-1

1. What are the differences between minerals and ores? 

2. What are the various steps involved in extraction of pure metals from their ores? 

3. What is the role of limestone in the extraction of iron from its oxide Fe2O3?

4. Which type of ores can be concentrated by froth floatation method? Give two 

examples for such ores. 

5. Out of coke and CO, which is better reducing agent for the reduction of ZnO? 

Why? 

6. Describe a method for refining nickel. 

7. Explain zone refining process with an example using the Ellingham diagram 

given below

8. (A) Predict the conditions under which 

(i) Aluminium might be expected to reduce magnesia. 

(ii) Magnesium could reduce alumina. 

(B) Carbon monoxide is more effective reducing agent than carbon below 

983K but, above this temperature, the reverse is true –Explain. 

(c) it is possible to reduce Fe2O3 by coke at a temperature around 1200K 

9. Give the uses of zinc. 

10. Explain the electrometallurgy of aluminium. 

11. Explain the following terms with suitable examples. (i) Gangue (ii) slag 

12. Give the basic requirement for vapour phase refining. 

13. Describe the role of the following in the process mentioned. 

(i) Silica in the extraction of copper

(ii) Cryolite in the extraction of aluminium. 

(iii) Iodine in the refining of Zirconium. 

(iv) Sodium cyanide in froth floatation. 

14. Explain the principle of electrolytic refining with an example. 

15. The selection of reducing agent depends on the thermodynamic factor: Explain 

with an example. 

16. Give the limitations of Ellingham diagram. 

17. Write a short note on electrochemical principles of metallurgy.

 UNIT-2

1. Write a short note on anamolous properties of the first element of p-block. 

2. Describe briefly allotropism in p- block elements with specific reference to carbon. 

3. Boron does not react directly with hydrogen. Suggest one method to prepare 

diborane from BF3. 

4. Give the uses of Borax. 

5. What is catenation ? describe briefly the catenation property of carbon. 

6. Write a note on Fisher tropsch synthesis. 

7. Give the structure of CO and CO2. 

8. Give the uses of silicones. 

9. AlCl3 behaves like a lewis acid. Substantiate this statement. 

10. Describe the structure of diborane. 

11. Write a short note on hydroboration. 

12. Give one example for each of the following 

 (i) icosogens (ii) tetragen (iii) prictogen (iv) chalcogen

13. Write a note on metallic nature of p-block elements. 

14. How will you identify borate radical? 

15. Write a note on zeolites. 

16. How will you convert boric acid to boron nitride? 

17. A hydride of 2nd period alkali metal (A) on reaction with compound of Boron 

(B) to give a reducing agent (C). identify A , B and C. 

18. A double salt which contains fourth period alkali metal (A) on heating at 

500K gives (B). aqueous solution of (B) gives white precipitate with BaCl2 and 

gives a red colour compound with alizarin. Identify A and B.

19. CO is a reducing agent . justify with an example

 UNIT-3

1.What is inert pair effect? 

2. Chalcogens belongs to p-block. Give reason. 

3. Explain why fluorine always exhibit an oxidation state of -1? 

4. Give the oxidation state of halogen in the following. 

a) OF2 b) O2F2 c) Cl2O3 d) I2O4

5. What are interhalogen compounds? Give examples. 

6. Why fluorine is more reactive than other halogens? 

7. Give the uses of helium. 

8. What is the hybridisation of iodine in IF7? Give its structure. 

9. Give the balanced equation for the reaction between chlorine with cold NaOH 

and hot NaOH. 

10. How will you prepare chlorine in the laboratory? 

11. Give the uses of sulphuric acid. 

12. Give a reason to support that sulphuric acid is a dehydrating agent. 

13. Write the reason for the anamolous behaviour of Nitrogen. 

14. Write the molecular formula and structural formula for the following

molecules. a) Nitric acid b) dinitrogen pentoxide c) phosphoric acid

 d) phosphine 

15. Give the uses of argon. 

16. Write the valence shell electronic configuration of group-15 elements. 

17. Give two equations to illustrate the chemical behaviour of phosphine. 

18. Give a reaction between nitric acid and a basic oxide. 

19. What happens when PCl5 is heated? 

20. Suggest a reason why HF is a weak acid, whereas binary acids of the all 

other halogens are strong acids. 

21. Deduce the oxidation number of oxygen in hypofluorous acid – HOF. 

22. What type of hybridisation occur in a) BrF5 b) BrF3 

 UNIT-4

1. What are transition metals? Give four examples. 

2. Explain the oxidation states of 4d series elements. 

3. What are inner transition elements? 

4. Justify the position of lanthanides and actinides in the periodic table. 

5. What are actinides? Give three examples. 

6. Why Gd3+ is colourless? 

7. Explain why compounds of Cu2+ are coloured but those of Zn2+ are colourless. 

8. Describe the preparation of potassium dichromate.

9. What is lanthanide contraction and what are the effects of lanthanide 

contraction? 

10. What are interstitial compounds? 

11. Calculate the number of unpaired electrons in Ti3+, Mn2+ and calculate the spin 

only magnetic moment. 

12. Write the electronic configuration of Ce4+ and Co2+. 

13. Explain briefly how +2 states becomes more and more stable in the first half 

of the first row transition elements with increasing atomic number. 

14. Which is more stable? Fe3+ or Fe2+ explain. 

15. Explain the variation in E0M

3+/M2+ 3d series. 

16. Compare lanthanides and actinides. 

17. Explain why Cr2+ is strongly reducing while Mn3+ is strongly oxidizing. 

18. Compare the ionization enthalpies of first series of the transition elements. 

19. Actinoid contraction is greater from element to element than the lanthanoid 

contraction, why? 

20. Out of Lu(OH)3 and La(OH)3 which is more basic and why? 

21. Why europium (II) is more stable than Cerium (II)? 

22. Why do zirconium and Hafnium exhibit similar properties? 

23. Which is stronger reducing agent Cr2+ or Fe2+? 

24. The E0M

2+/M value for copper is positive. Suggest a possible reason for this. 

25. predict which of the following will be coloured in aqueous solution Ti2+ , V3+ , Sc4+, Cu+,Sc3+, Fe3+, Ni2+ and Co3+ 

26. Describe the variable oxidation state of 3d series elements. 

27. Which metal in the 3d series exhibits +1 oxidation state most frequently and 

why? 

28. Why first ionization enthalpy of chromium is lower than that of zinc? 

29. Transition metals show high melting points why? 

 UNIT-5

1. Write the IUPAC names for the following complexes. 

i) Na2[Ni(EDTA)] ii) [Ag (CN)2]-

 iii) [Co(en)3] (SO⁴)3

iv) [Co(ONO)(NH3)5]2+ 

 v) [Pt(NH3)2Cl (NO²)]

2. Write the formula for the following coordination compounds. 

a) potassiumhexacyanidoferrate(II) b) pentacarbonyliron(0) 

c) pentaamminenitrito −ҝ −N-cobalt(III)ion d) hexaamminecobalt(III)sulphate 

e) sodiumtetrafluoridodihydroxidochromate(III) 

3. Arrange the following in order of increasing molar conductivity 

i) Mg[Cr(NH3) Cl5] ii) [Cr(NH3)5Cl]3 [CoF6]2 iii) [Cr(NH3)3Cl3]

4. Ni2+ is identified using alcoholic solution of dimethyl glyoxime. Write the 

structural formula for the rosy red precipitate of a complex formed in the 

reaction. 

5. [CuCl4]2-

 exists while [CuI4]2- does not exist why? 

8. Give an example of coordination compound used in medicine and two examples 

of biologically important coordination compounds. 

9. Based on VB theory explain why [Cr(NH3)6]

3+ is paramagnetic, while [Ni(CN)4]2-

is diamagnetic. 

9. Draw all possible geometrical isomers of the complex [Co(en)2 Cl2]+ and identify 

the optically active isomer. 

10. [Ti(H2O)6]

3+ is coloured, while [Sc(H2O)6]

3+ is colourless- explain. 

11. Give an example for complex of the type [Ma2b2c2] where a, b, c are 

monodentate ligands and give the possible isomers. 

12. Give one test to differentiate [Co(NH3)5Cl]SO4 and [Co(NH3)5SO4]Cl. 

13. In an octahedral crystal field, draw the figure to show splitting of d orbitals. 

14. What is linkage isomerism? Explain with an example. 

15. Write briefly about the applications of coordination compounds in volumetric 

analysis. 

16. Classify the following ligand based on the number of donor atoms. 

a) NH3 b) en c) ox2- d) triaminotriethylamine e) pyridine

17. Give the difference between double salts and coordination compounds. 

18. Write the postulates of Werner’s theory. 

19. [Ni(CN)4]2-

 is diamagnetic, while [NiCl4]2-

is paramagnetic ,explain using 

crystal field theory. 

20. Why tetrahedral complexes do not exhibit geometrical isomerism. 

21. Explain optical isomerism in coordination compounds with an example. 

22. What are hydrate isomers? Explain with an example. 

23. What is crystal field splitting energy? 

24. What is crystal stabilization energy (CFSE) ? 

25. A solution of field [ Ni(H2O)6]

2+ is green, whereas a solution of [Ni(CN)4]2-is colorless - Explain 

26. Discuss briefly the nature of bonding in metal carbonyls. 

27. What is the coordination entity formed when excess of liquid ammonia is added to an aqueous solution of copper sulphate? 

28. On the basis of VB theory explain the nature of bonding in [Co(C2O4)3]3-

29. What are the limitations of VB theory? 

30. Write the oxidation state, coordination number , nature of ligand, magnetic 

property and electronic configuration in octahedral crystal field for the complex 

K4[Mn(CN)6] .

 UNIT-6

1. Define unit cell. 

2. Give any three characteristics of ionic crystals. 

3. Differentiate crystalline solids and amorphous solids. 

4. Classify the following solids a. P4 b. Brass c. diamond d. NaCl e. Iodine

5.Explain briefly seven types of unit cell. 

6. Distinguish between hexagonal close packing and cubic close packing. 

7. Distinguish tetrahedral and octahedral voids. 

8. What are point defects? 

9. Explain Schottky defect. 

10. Write short note on metal excess and metal deficiency defect with an example. 

11. Calculate the number of atoms in a fcc unit cell. 

12. Explain AAAA and ABABA and ABCABC type of three dimensional packing 

with the help of neat diagram. 

13. Why ionic crystals are hard and brittle? 

14. Calculate the percentage efficiency of packing in case of body centered cubic 

crystal. 

15. What is the two dimensional coordination number of a molecule in square close 

packed layer? 

16. Experiment shows that Nickel oxide has the formula Ni0.96O1.00. What fraction 

of Nickel exists as of Ni

2+ and Ni3+ ions? 

17. What is meant by the term “coordination number”? What is the coordination 

number of atoms in a bcc structure? 

18. Write a note on Frenkel defect. 

 UNIT-7

1. Define average rate and instantaneous rate. 

2. Define rate law and rate constant. 

3. Derive integrated rate law for a zero order reaction. A→product.

4. Define half life of a reaction. Show that for a first order reaction half life is 

independent of initial concentration. 

5. What is an elementary reaction? Give the differences between order and 

molecularity of a reaction. 

6. Explain the rate determining step with an example. 

7. Describe the graphical representation of first order reaction. 

8. Write the rate law for the following reactions. 

(a) A reaction that is 3/2 order in x and zero order in y. 

(b) A reaction that is second order in NO and first order in Br2. 

9. Explain the effect of catalyst on reaction rate with an example. 

10. The rate law for a reaction of A, B and C has been found to be 

 rate =K [A]2 [B][L]

3/2 . How would the rate of reaction change when 

(i) Concentration of [L] is quadrupled 

(ii) Concentration of both [A] and [B] are doubled 

(iii) Concentration of [A] is halved 

 (iv) Concentration of [A] is reduced to (1/3) and concentration of [L] is 

quadrupled. 

11. Explain briefly the collision theory of bimolecular reactions. 

12. Write Arrhenius equation and explains the terms involved. 

13. Explain pseudo first order reaction with an example. 

14. How do concentrations of the reactant influence the rate of reaction? 

15. How do nature of the reactant influence rate of reaction?

16. The rate constant for a first order reaction is 1.54 × 10-1 . Calculate its half life 

time. 

 UNIT-8

1. What are lewis acids and bases? Give two examples for each.

2. Discuss the Lowery – Bronsted concept of acids and bases.

3. Indentify the conjugate acid base pair for the following reaction in aqueous 

solution

4. Account for the acidic nature of HClO4 . In terms of Bronsted – Lowry theory, 

identify its conjugate base.

5. When aqueous ammonia is added to CuSO4 solution, the solution turns deep 

blue due to the formation of tetramminecopper (II) complex, among H2O and 

NH3 Which is stronger Lewis base? [Cu(H2 O)4 ]2++4NH3 (aq) → [Cu(NH3 )4 ]2+

(aq)

6. Define solubility product

7. Define ionic product of water. Give its value at room temperature.

8. Explain common ion effect with an example

9. Derive an expression for Ostwald’s dilution law

10. Define pH

11. Derive an expression for the hydrolysis constant and degree of hydrolysis of 

salt of strong acid and weak base

12. Write the expression for the solubility product of Ca3(PO4 )2 .

13. Write the expression for the solubility product of Hg2 Cl2 . 

 UNIT-9

1. Define anode and cathode 

2. Why does conductivity of a solution decrease on dilution of the solution?

3. State Kohlrausch Law. How is it useful to determine the molar conductivity of 

weak electrolyte at infinite dilution?

4. Describe the electrolysis of molten NaCl using inert electrodes.

5. State Faraday’s Laws of electrolysis.

6. Describe the construction of Daniel cell. Write the cell reaction. 

7. Why is anode in galvanic cell considered to be negative and cathode positive 

electrode? 

8. Which of 0.1M HCl and 0.1 M KCl do you expect to have greater and why? 

9. Arrange the following solutions in the decreasing order of specific conductance. 

i) 0.01M KCl ii) 0.005M KCl iii) 0.1M KCl iv) 0.25 M KCl v) 0.5 M KCl 

10. Why is AC current used instead of DC in measuring the electrolytic 

conductance? 

11. Two metals M1 and M2 have reduction potential values of -xV and +yV 

respectively. Which will liberate H2 and H2SO4.

12. Derive an expression for Nernst equation

13. Write a note on sacrificial protection.

14. Explain the function of H2 – O2 fuel cell.

15.Ionic conductance at infinite dilution of Al3+ and SO42-

UNIT-10
1.Give two important characteristics of physisorption
2. Differentiate physisorption and chemisorption
3. In case of chemisorption, why adsorption first increases and then decreases with
temperature?
4. Which will be adsorbed more readily on the surface of charcoal and why; NH3
or CO2 ?
5. Heat of adsorption is greater for chemisorptions than physisorption. Why?
6. Peptising agent is added to convert precipitate into colloidal solution. Explain 
with an example.
7. What happens when a colloidal sol of Fe(OH)3 and As2O3 are mixed?
8. What is the difference between a sol and a gel?
9. Why are lyophillic colloidal sols are more stable than lyophobilc colloidal sol.
10. Addition of Alum purifies water. Why?
11. What are the factors which influence the adsorption of a gas on a solid?
12. What are enzymes? Write a brief note on the mechanism of enzyme catalysis.
13. What do you mean by activity and selectivity of catalyst?
14. Describe some feature of catalysis by Zeolites.
15. Give three uses of emulsions.
16. Why does bleeding stop by rubbing moist alum?
17. Why is desorption important for a substance to act as good catalyst?
18. Comment on the statement: Colloid is not a substance but it is a state of 
substance.
19. Explain any one method for coagulation.
20. Write a note on electro osmosis.
21. Write a note on catalytic poison.
22. Explain intermediate compound formation theory of catalysis with an example.
23. What is the difference between homogenous and heterogenous catalyst?
24. Describe adsorption theory of catalysis.
 UNIT-11
1. Identify the product (s) is / are formed when 1 – methoxy propane is heated with 
excess HI. Name the mechanism involved in the reaction
2. Draw the major product formed when 1-ethoxyprop-1-ene is heated with one 
equivalent of HI.
3. Suggest a suitable reagent to prepare secondary alcohol with identical group 
using Grignard reagent.
4. What is the major product obtained when two moles of ethyl magnesium 
bromide is treated with methyl benzoate followed by acid hydrolysis.
5. Predict the major product, when 2-methyl but -2-ene is converted into an alcohol 
in each of the following methods. (i.) Acid catalysed hydration (ii.) 
Hydroboration (iii.) Hydroxylation using bayers reagent
6. Arrange the following in the increasing order of their boiling point and give a 
reason for your ordering (i.) Butan – 2- ol, Butan -1-ol, 2 –methylpropan -2-ol
 (ii.) Propan -1-ol, propan -1,2,3-triol, propan -1,3 – diol, propan -2-ol
7. Can we use nucelophiles such as NH3 ,CH3O￾for the Nucleophilic substitution 
of alcohols.
8. Is it possible to oxidise t – butyl alcohol using acidified dichromate to form a 
carbonyl compound.
9. What happens when 1-phenyl ethanol is treated with acidified KMnO4 .
10. Write the mechanism of acid catalysed dehydration of ethanol to give ethane.
11. How is phenol prepared form i) chloro benzene ii) isoprophy benzene
12. Explain Kolbe’s reaction.
13. Writes the chemical equation for Williamson synthesis of 2-ethoxy – 2- methyl 
pentane starting from ethanol and 2 – methyl pentan -2-ol.
14. Write the structure of the aldehyde, carboxylic acid and ester that yield 4-
methylpent -2-en-1-ol.
15. What is metamerism? Give the structure and IUPAC name of metamers of 2-
methyoxy propane
16. How are the following conversions effected i) benzylchloride to benzylalcohol 
ii) benzyalalcohol to benzoic acid
17. How will you convert acetylene into n-butyl alcohol?
 UNIT-12
1. How is propanoic acid is prepared starting from (a) an alcohol (b) an alkylhalide 
(c) an alkene
2. How will you convert benzaldehyde into the following compounds (i) 
benzophenone (ii) benzoic acid (iii) hydroxy phenyl acetic acid.
3. What is the action of HCN on (i) propanone (ii) 2,4- dicholorobenzaldehyde.
4. Write the structure of the major product of the aldol condensation of 
benzaldehyde with acetone.
5. How are the following conversion effected (i) propanal into butanone (ii) hex-3-
yne into hexan-3-one (iii) phenylmethanal into benzoic acid (iv) 
phenylmethanal into benzoin
 UNIT-13
1. Write down the possible isomers of the C4H3NO2 give their IUPAC names.
2. There are two isomers with the formula CH3NO2 . How will you distinguish 
between them?
3. What happends when i. 2 – Nitropropane boiled with HCl
 ii. Nitrobenezenelectrolytic reduction in strongly acidic medium.
 iii. Oxidation of tert – butylamine with KMnO4
 iv. Oxidation of acetoneoxime with trifluoroperoxy acetic acid.
4. How will you convert nitrobenzene into i) 1,3,5 – trinitrobenzene ii) o and p￾nitrophenoln iii) m – nitro aniline iv) azoxybenzene v) hydrozobenzene
 vi) N – phenylhydroxylamine vii) aniline
5. Write short notes on the following i) Hofmann’s bromide reaction ii)
Ammonolysis iii) Gabriel phthalimide synthesis iv) Schotten – Baumann reaction
v) Carbylamine reaction vi) Mustard oil reaction vii) Coupling reaction viii)
Diazotisation ix) Gomberg reaction
6. How will you distinguish between primary, secondary and tertiary alphatic 
amines.
7. Account for the following
 i. Aniline does not undergo Friedel – Crafts reaction
 ii. Diazonium salts of aromatic amines are more stable than those of aliphatic 
amines
 iii. pKb of aniline is more than that of methylamine
 iv. Gabriel phthalimide synthesis is preferred for synthesising primary amines.
 v. Ethylamine is soluble in water whereas aniline is not
 vi. Amines are more basic than amides
 vii.Although amino group is o – and p – directing in aromatic electrophilic 
substitution reactions, aniline on nitration gives a substantial amount of m –
nitroaniline.
8. How will you prepare propan-1-amine from (i) butane nitrile (ii) propenamide 
(iii) 1- nitro propane
9. How will you convert diethylamine into (i) N,N-diethylacetamide (ii) N￾nitrosodiethylamine 
 UNIT-14
1. What type of linkages hold together monomers of DNA?
2. Give the differences between primary and secondary structure of proteins.
3. Name the Vitamins whose deficiency cause i) rickets ii) scurvy
4. Write the Zwitter ion structure of alanine.
5. Give any three difference between DNA and RNA.
6. Write a short note on peptide bond.
7. Give two difference between Hormones and vitamins.
8. Write a note on denaturation of proteins.
9. What are reducing and non – reducing sugars?
10.Why carbohydrates are generally optically active.
11.Classify the following into monosaccharides, oligosaccharides and 
polysaccharides. i) Starch ii) fructose iii) sucrose iv) lactosethermosetting.

12.How are vitamins classified.
13.What are harmones? Give examples.
14.Write the structure of all possible dipeptides which can be obtained form 
glycine and alanine.
15.Define enzymes.
16.Writhe the structure of α-D (+) glucophyranose.
17.What are different types of RNA which are found in cell.
18.Write a note on formation of α-helix .
19.What are the functions of lipids in living organism.
20.Is the following sugar, D – sugar or L – sugar?
 UNIT-15
1. Which chemical is responsible for the antiseptic properties of dettol.
2. What are antibiotics?
3. Name one substance which can act as both analgesic and antiphyretic
4. Write a note on synthetic detergents
5. How do antiseptics differ from disinfectants?
6. What are food preservatives?
7. Who do soaps not work in hard water?
8. What are drugs? How are they classified
9. How the tranquilizers work in body.
10. Write the structural formula of aspirin.
11. Explain the mechanism of cleansing action of soaps and detergents
12. Which sweetening agent are used to prepare sweets for a diabetic patient?
13. What are narcotic and non – narcotic drugs. Give examples
14. What are anti fertility drugs? Give examples.
15. Write a note on co –polymer
16. What are bio degradable polymers? Give examples.
17. How is terylene prepared?
18. Write a note on vulcanization of rubber
19. Classify the following as linear, branched or cross linked polymers a) Bakelite 
b) Nylon c) polythene
20. Differentiate thermoplastic and thermosetting

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