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Tamil Nadu State Board · CLASS 12th · Chemistry

TAMIL NADU STATE BOARD CLASS 12 CHEMISTRY 2025

48 questions from this CLASS 12th Chemistry paper. Log in as a CLASS 12th student to view solutions.

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Q1 mcq 1 mark
During the decomposition of H$_2$O$_2$ to give dioxygen, 48 g O$_2$ is formed per minute at certain point of time. The rate of formation of water at this point is :
  • A. 2.25 mol min$^{-1}$
  • B. 0.75 mol min$^{-1}$
  • C. 3.0 mol min$^{-1}$
  • D. 1.5 mol min$^{-1}$

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Q2 mcq 1 mark
How many moles of I$_2$ are liberated when 1 mole of potassium dichromate react with potassium iodide ?
  • A. 3
  • B. 1
  • C. 4
  • D. 2

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Q3 mcq 1 mark
Non-stick cookwares generally have a coating of a polymer, whose monomer is :
  • A. chloroethene
  • B. ethane
  • C. 1,1,2,2-tetrafluoroethane
  • D. prop-2-enenitrile

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Q4 mcq 1 mark
The compound that reacts with nitrous acid to give yellow oily liquid is __________.
  • A. N-methylaniline
  • B. Nitro benzene
  • C. N,N-dimethyl aniline
  • D. Aniline

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Q5 mcq 1 mark
Boric acid is an acid because its molecule :
  • A. combines with proton to form water molecule.
  • B. contains replaceable H$_1$ ion.
  • C. accepts OH$^-$ from water, releasing proton.
  • D. gives up a proton.

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Q6 mcq 1 mark
In an electrical field, the particles of a Colloidal system move towards cathode. The coagulation of the same sol is studied using (i) K$_2$SO$_4$, (ii) Na$_3$PO$_4$, (iii) K$_4$[Fe(CN)$_6$] and (iv) NaCl. Their coagulating power should be :
  • A. (iii) > (ii) > (i) > (iv)
  • B. (i) > (ii) > (iii) > (iv)
  • C. (ii) > (i) > (iv) > (iii)
  • D. None of these

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Q7 mcq 1 mark
Assertion: Bond dissociation energy of Fluorine is greater than Chlorine gas. Reason : Chlorine has more electronic repulsion than Fluorine.
  • A. Assertion is true but Reason is false.
  • B. Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  • C. Both Assertion and Reason are false.
  • D. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

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Q8 mcq 1 mark
In calcium fluoride, having the flurite structure, the coordination number of Ca$^{21}$ ion and F$^-$ ion are :
  • A. 8 and 4
  • B. 4 and 2
  • C. 4 and 8
  • D. 6 and 6

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Q9 mcq 1 mark
The secondary structure of a protein refers to _________.
  • A. sequence of α-amino acids
  • B. fixed configuration of the polypeptide backbone
  • C. α-helical backbone
  • D. hydrophobic interaction

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Q10 mcq
At 258C, ionic product constant $K_w$ of water is 1.00×10$^{-14}$. Its value at 408C is __________.
  • A. 1.00×10$^{-14}$
  • B. 1.14×10$^{-15}$
  • C. 2.71×10$^{-14}$
  • D. 2.95×10$^{-15}$

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Q11 mcq
What is the oxidation number of the central metal ion in the complex, [Pt(NO$_2$)(H$_2$O)(NH$_3$)$_2$]Br ?
  • A. 14
  • B. 12
  • C. 16
  • D. 13

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Q12 mcq
The number of electrons that have a total charge of 9650 coulombs is :
  • A. 6.022×10$^{22}$
  • B. 6.22×10$^{23}$
  • C. 6.022×10$^{-34}$
  • D. 6.022×10$^{24}$

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Q13 mcq
Which one of the following is the Strongest acid ?
  • A. 4-nitrophenol
  • B. 2-nitrophenol
  • C. 3-nitrophenol
  • D. 4-chlorophenol

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Q14 mcq
3 5 KCN H O PCl 3CH Br (A) (B) (C)→ → → + Product (C) is :
  • A. chloro acetic acid
  • B. α-chlorocyano ethanoic acid
  • C. acetylchloride
  • D. none of these

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Q15 mcq
Extraction of gold and silver involves leaching with cyanide ion. Silver is later recovered by :
  • A. Displacement with Zinc
  • B. Distillation
  • C. Liquation
  • D. Zone refining

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Q16 short answer
Which type of ores can be concentrated by froth floatation method ? Give an example for ores.

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Q17 short answer
What happens when $PCl_5$ is heated ?

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Q18 short answer
Why do Zirconium and Hafnium exhibit similar properties ?

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Q19 short answer
Define Solubility Product.

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Q20 short answer
Define Equivalent Conductance.

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Q21 short answer
Peptising agent is added to convert precipitate into colloidal solution. Explain this statement with an example.

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Q22 short answer
Write Gattermann - Koch reaction.

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Q23 short answer
How are drugs classified ?

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Q24 short answer
Find the products X and Y in the following reactions.

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Q25 short answer
Describe a method for refining Nickel.

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Q26 short answer
Write short notes on bleaching action of Sulphur dioxide.

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Q27 short answer
What are hydrate isomers ? Explain with an example.

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Q28 short answer
Distinguish tetrahedral and octahedral voids.

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Q29 short answer
What are the limitations of Freundlich adsorption isotherm ?

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Q30 short answer
Identify compounds A, B and C in the following sequence of reaction.

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Q31 short answer
What is Condensation Polymer ? Give two examples.

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Q32 short answer
Mention any three functions of lipids in living organism.

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Q33 short answer
The rate of a first order reaction is 1.54×10$^{-3}$ $s^{-1}$. Calculate its half life period.

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Q33 short answer
The rate constant for a first order reaction is $1.54 \times 10^{-3} s^{-1}$. Calculate its half life time.

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Q35 long answer
Describe the role of the following in the process mentioned. (1)Cryolite in the extraction of Aluminium. (2)Iodine in the refining of Zirconium.

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Q36 long answer
State any three properties of inter halogen compounds.

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Q37 long answer
How will you identify borate radical ?

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Q38 long answer
Give the uses of Borax.

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Q39 long answer
Describe the preparation of potassium dichromate.

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Q40 long answer
Write the postulates of Werner’s theory.

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Q41 long answer
Write a short note on metal excess defect with an example.

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Q42 long answer
Explain Pseudo first order reaction with an example.

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Q43 long answer
Calculate the pH of 0.1 M CH$_3$COOH solution. Dissociation constant of acetic acid is 1.8×10$^{-5}$.

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Q44 long answer
Derive an expression for Nernst equation.

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Q45 long answer
How will you convert (i)Ethyl alcohol → Ethene (ii)Ethylene glycol → 1,4-dioxane (iii)Glycerol → Acrolein

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Q46 long answer
An organic compound (A) of molecular formula C$_7$H$_6$O undergoes Cannizaro reaction. Compound (A) also reacts with Chlorine in the presence of Conc.FeCl$_3$ to give Compound (B). Compound (A) reacts with Chlorine in the absence of catalyst to give Compound (C). Identify A, B and C with suitable reactions.

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Q47 long answer
How will you distinguish between nitro and aci form of CH$_3$NO$_2$ ?

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Q48 long answer
What are the types of RNA which are found in cell ?

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