📚 12th Chemistry Most Repeated Questions – Tamil Nadu Board 2026
💡 12th Chemistry Top 20 Five Marks Public exam 2026
💡 12th Chemistry Top 30 Three Marks Public exam 2026
💡 12th Chemistry Top 50 Two Marks Public exam 2026
💡 12th Chemistry Important Compulsory Questions Public exam 2026
💡 12th Chemistry Naming Reactions – Identify A, B, C | Previous Year Questions with Answers
💡 12th Chemistry Score Centum plan 2026
📚 12th Chemistry Chapter Wise Important Questions – Tamil Nadu Board 2026
5 Marks : Appeared Once In Question Paper
- Explain electromagnetic separation?(1) Ln1
- Give the uses of zinc. Ln1 Q8
- Extraction of copper from copper pyrites?Ln1 pg8
- How will you prepare producer gas?Ln2 Pg43
- Types of silicates and give one example?48(1) Ln2
- What happens when borax is heated?Pg34 Ln2
- Write a note on metallic nature of p-block elements. Q11 Ln2
- Uses of potash alum?Ln2 Pg40
- Describe briefly allotropism in p- block elements with specific reference to carbon.?Ln2 Q2
- Write short notes on graphene?pg43(1) Ln2
- Why does bleeding stop by rubbing moist alum? Pg 40 Ln2
- Give one example for each of the following Ln 2 Q10
- Complete the following reactions?Ln3
- P4 + NaOH + H2O ——->
- XeF6 +H2O —->
- Cu +conc.H2SO4 ——>
- Write the molecular formula and structural formula for the following molecules. BB14 (1) Ln3
- a) Nitric acid b) dinitrogen pentoxide c) phosphoric acid d) phosphine
- Give a reaction between nitric acid and a basic oxide.Q18 Ln3
- Write the structure of marshall’s acid? Ln3 Pg81
- Uses of Xenon & Radon Ln3 Pg94
- Uses of sulphuric acid?Ln3 Pg79
- Transition metals form complexes – why?Ln4(1)
- List out the properties of interstitial compounds?Ln4
- List out the uses of potassium di chromate?Ln4(1)
- What are the consequences of Lanthanoid contraction?Ln4
- State Hume – Rothery rule?Ln4 Pg111
- Using VB theory explain the following:Ln5 Pg150(1)
- A.[Ni(CN)4]4-B.[Fe(CN)6]3- C.[Ni(co)4] D.[Ni(co)4]4-
- Explain the crystal field splitting in octahedral complexes?(1) Ln5
- Describe the nature of bonding in metallic carbonyls?(1) Ln5
- Give two examples for zero order reaction?(1) Ln7
- Write two examples of first-order reactions?(1) Ln7
- Write the expression for the solubility product of Hg2cl2?(1) Ln8
- Define solubility product?(1) Ln8
- Define pH? Ln8 Q13
- Establish a relationship between the solubility product and molar solubility for the following a) BaSO b) Ag (CrO ) Example 8.10 Pg26 ln8
- State faradays first law?(1) Ln9
- Describe the construction of Daniel cell. Write the cell reaction.?BB6 (1) Ln9
- What are the various methods used for coagulation?(1) Ln10
- Various application of colloids?Ln10 Pg98
- What are active centers?(1) Ln10
- How colloids are used in tanning of leather and in Rubber industry?(1) Ln10
- What are promoters?Pg79(1) Ln10
- Write a note on electrophoresis?Ln10 Pg94
- What is brownian movement?ln10 Pg 93
- Explain williamson’s synthesis with mechanism?(1) Ln11
- What is baeyer’s reagent? How it is useful to convert ethane to ethane-1,2-diol?Ln11(1) Ln11
- Why aniline does not undergo Friedel craft’s reaction?(1)Ln11
- Anisole – Halogenation , Nitration?Ln11 Pg138
- Write any three electrophilic substitution of phenol(Nitrosation,Nitration,Halogenation,Sulphonation)Ch11 Pg128
- What is the action of HCN on Ln12 Q8
- benzoin condensation reaction?Ln12 Pg164
- Why ionic crystals are hard and brittle?Q13 Ln6
- What is Libermann nitroso test?(1)Ln13
- Write a short note on Thorpe nitrile condensation reaction? Ln13
- Reduction of nitro benzene under different conditions?pg204(1) Ln13
- What are vitamins? give two examples?(1) Ln14
- Classify the following into monosaccharides, oligosaccharides and polysaccharidesLn14 Q11
- How do you classify the following into various class of drugs?Ln15(1)
- A)Milk of Magnesia B)Aspirin c)Penicillin
- How nylon-2-nylon-6 is prepared?Ln15
- What are called antacids?Give example?(1)
- Classify the following as linear, branched or cross linked polymers BB17(1)
- a) Bakelite b) Nylon-6,6 c) LDPE d) HDPE
- How teflon is prepared?pg288(1)
- Explain the clensing action of soap?Ln15(1)
3 Marks : Appeared Once In Question Paper
- Give the limitations of ellingham diagram?(2)Ln1
- Preparation of phosphine by using caustic soda(NAOH)?pg68(1)Ln3
- Describe the position of f block elements in the periodic table?Pg118(1)Ln4
- Out of Lu(OH)3 and La(OH)3 which is more basic and why?Q19 Ln4
- Why do zirconium and Hafnium exhibit similar properties?Q21 Ln4
- On the basis of VB theory, explain the nature of bonding in [Co(C₂O₄)₃]³⁻ ?(1) Ln5
- Write short note on – π-Back bonding in metal carbonyl?(1) Ln5
- Imperfections in solid play an important role in various process.Justify?Ln6 Pg192
- How do concentrations of the reactant influence the rate of reaction?Q21 Ln7
- How does ethane-1,2-diol react with anhydrous zncl2 under pressure?(1) Ln8
- Discuss the Lowry-Bronsted concept of acids and bases.(1) Ln8
- Define ionic product of water. Give its value at room temperature. ?Ln8 Q10
- Derive an expression for the hydrolysis constant and degree of hydrolysis of salt of strong acid and weak base?Ln8 Q18
- Explain the function of H2 O2 fuel cell. L9 Q26
- How will you protect metals from corrosion?(1) Ln9
- Mention the anode,Cathode,Electrolyte and the uses of mercury button cell?(1) Ln9
- Explain intermediate compound formation theory of catalysis?(1) Ln10
- Write a notes on Helmholt’s electriccal double layer?(1) Ln10
- Explain the characterisics of a catalyst?(1)Pg78 Ln10
- Define Heterogeneous catalysis?Pg77(1) Ln10
- Peptising agent is added to convert precipitate into colloidal solution. Explain with an example. Q6 Ln10
- Write note on emulsions,types of emulsions and any two uses of emulsion?Ln10 Pg97
- Explain Freundlich adsorption isotherm?Ln10 Pg74
- what is optimum temperature in enzyme catalysed reaction?pg84(1) Ln10
- Identify the enzyme catalyst in the following reactions?Pg83(1) Ln10
- Oxidation of ethanol into acetic acid
- Hydrolysis of starch into maltose
- Hydrolysis of urea
- How do you prepare the following? A)Picric acid B)TNGLn11(1) Ln 11
- What is the major product obtained when 2,3 – dimethyl pentan -3 – ol is heated in the presence of H S2 4 O .Pg117 Evaluate Ln 11
- Test to differentiate alcohol and phenol?(1) Ln 11
- What is Glycerose ? How is it formed?Ln11 pg121
- Explain the coupling reaction of phenol?Ln11 Pg131
- Action of con h2so4 on glycol?Ln11 Pg120
- Conversion of ethyl alcohol to ethene?Ln11 pg115 Elimination reaction | Ethylene glycol to Ethanal
- Uses of carboxylic acids and its derivatives?(1) Ln12
- What is Perkins reaction?Ln12 Pg165
- Reducing action of formic acid?Ln12 Pg177
- What is metamerism? Give the structure and IUPAC name of metamers of 2-methyoxy propane ?Ln12 Q15
- How will you prepare propan – 1- amine from Ln13 Q10
- What happens when i. 2 – Nitropropane boiled with HCl ii. Nitrobenzene undergo electrolytic-reduction in strongly acidic medium Ln13 Q3
- Explain Levine and Hauser acetylation?Ln13 Pg225
- Discuss the importance of proteins?Ln14(1)
- Write a note on denaturation of proteins ?Q8 Ln14
- What is called Mutarotation?Ln14 Pg244
- Uses of teflon?Ln15 Pg288
- Give one example for ?Ln15
- A)Tranquiliser B)antithistamin C)artificial sweetening agent
- Convert the following : A.Methyl acetate – ethyl acetate B.Benzaldehyde to Malachite green dye C.Ethane Nitrile to Ethanal
2 Marks : Appeared Once In Question Paper
- Explain Acid leaching with example. (Ln1 – 1)
- How copper matte is formed? (Ln1 – 1)
- What are the uses of boric acid? (Ln2 – 1)
- What are silicones? What are its types? (Ln2 – 1)
- How bleaching powder is prepared? (Ln3 – 1)
- Uses of oxygen. (Ln3 – 1)
- Why HF cannot be stored in glass bottles?Ln3 Pg88
- What is Bayer’s reagent? (Ln4 – 1)
- Mention the conditions of formation of alloys?Ln4 Pg111
- Write the IUPAC name of the following compounds. (Ln5 – 1)
- Explain coordination isomerism with example. (Ln5 – 1)
- Write IUPAC ligand name for the following. (Ln5 – 1)
- Define central atom in coordination compounds. (Ln5 – 1)
- Write the formula of zeise’s salt and Magnu’s green salt?Ln5 Pg136
- What is linkage isomerism? (Ln5 – 1)
- What are “F” Centres?Ln Pg194
- If 6 close packed spheres, calculate octahedral & tetrahedral voids. (Ln6 – 1)
- Radius of sodium atom in BCC structure calculation. (Ln6 – 1)
- What is metal deficiency defect? (Ln6 – 1)
- What is metal excess defect? (Ln6 – 1)
- Classify diamond, brass, NaCl, naphthalene into types of solids. (Ln6)
- Define half life period. (Ln7 – 1)
- Acidic nature of HClO₄ – Bronsted Lowry theory. (Ln8 – 1)
- Define buffer solution. (Ln8 – 1)
- What are conjugate acid-base pairs? (Ln8 – 1)
- Why conductivity decreases on dilution? (Ln9 – 1)
- Define equivalent conductance. (Ln9 – 1)
- Define molar conductance. (Ln9 – 1)
- Silver nitrate electrolysis calculation. (Ln9)
- Calculate EMF of Zn|Zn²⁺ || Cu²⁺|Cu cell. (Ln9)
- Factors affecting adsorption. (Ln10 – 1)
- Catalytic poisons with example. (Ln10 – 1)
- Negative catalysis. (Ln10 – 1)
- Why lyophilic sols are more stable than lyophobic sols? (Ln10)
- Tests for phenol. (Ln11 – 1)
- Product of 1-methoxypropane with HI. (Ln11 – 1)
- Glycerol reaction with KHSO₄. (Ln11 – 1)
- Saponification reaction. (Ln11 – 1)
- Anisole reaction with HI. (Ln11 – 1)
- Rosenmund reduction reaction. (Ln12 – 1)
- Popoff’s rule. (Ln12 – 1)
- Convert acetone to propane. (Ln12 – 1)
- Write note on isoelectric point. (Ln14 – 1)
- What are hormones? Give example. (Ln14)
- What are disinfectants? (Ln15)
- What are antibiotics? Give example. (Ln15 – 1)
Compulsory Additional
Q1.The time for half change in a first order decomposition of a substance A is 60 seconds. Calculate the rate constant. How much of A will be left after 180 seconds?Ln7 Q25
