Chemistry · Class 12 Science

Odisha Chse Class 12 Chemistry — Real Previous-Year Papers

with complete answers

Real previous-year board papers, year by year — the official exam pattern, the full question paper, and every question solved the concept-first way. Distinct from the chapter-wise textbook bank.

2018–2026
Years of papers: 7
Total Papers: 7
Real Board Papers: 0
Sample papers: 288
Real-paper Q & A: 0
Sample-paper Q & A

Real board-paper questions available, by year

49 Q2026complete

49 Q2025complete

39 Q2024complete

39 Q2023complete

—2022Paper not available

—2021Exam cancelled (COVID-19)

39 Q2020complete

—2019Paper not available

34 Q2018complete

2022 — Paper not available: We publish a CHSE Odisha +2 Science board question paper only after verifying it against a genuine printed original. No such verified paper is available for this year from the sources we check, so we show none rather than an unconfirmed copy.

2021 — Exam cancelled (COVID-19): The Council of Higher Secondary Education, Odisha (CHSE) cancelled the +2 Science Class-12 board exam for this year statewide due to COVID-19; no annual question paper was ever conducted or printed, so none exists to publish.

2019 — Paper not available: We publish a CHSE Odisha +2 Science board question paper only after verifying it against a genuine printed original. No such verified paper is available for this year from the sources we check, so we show none rather than an unconfirmed copy.

Odisha CHSE +2 Science Board Exam 2026 · Set ANNUAL

Real board examination

About this paper

The real Class-12 board examination held in 2026. Every question below is solved the concept-first way. Sample papers are labelled honestly — never shown as a past exam.

Total marks: 70
Questions: 37
Duration: 180 min
Sections: 4

The marks / questions / duration above are the official exam pattern. We currently have 49 of this paper’s questions (132% of the full paper), with 49 fully solved. Questions we couldn’t yet extract or verify are held — never shown as complete.

Sections & marks

Section	Type	Questions	Marks each	Total
ASection A	Objective (MCQ) -- all compulsory, 1 mark each	20	1	20
BSection B	Short answer -- answer any 7 of 12 printed, 2 marks each	7	2	14
CSection C	Short answer -- answer any 7 of 12 printed, 3 marks each	7	3	21
DSection D	Long answer -- answer any 3 of 5 printed, 5 marks each	3	5	15
Total		37		70

The question paper

The questions we hold for this paper, laid out by section. Solutions are on the Answers tab.

Board Examination

Chemistry

Odisha CHSE +2 Science Board Exam 2026 · Set ANNUAL

Series/Set: ANNUALRoll No. ________

Time Allowed: 3 hoursMaximum Marks: 70

General Instructions

This question paper contains 37 questions divided into 4 sections — A, B, C, D.
Section A comprises 20 questions of 1 mark each (Objective (MCQ) -- all compulsory, 1 mark each).
Section B comprises 7 questions of 2 marks each (Short answer -- answer any 7 of 12 printed, 2 marks each).
Section C comprises 7 questions of 3 marks each (Short answer -- answer any 7 of 12 printed, 3 marks each).
Section D comprises 3 questions of 5 marks each (Long answer -- answer any 3 of 5 printed, 5 marks each).

Above is the official exam pattern. The questions printed below are those we currently hold for this paper.

Section A

Objective (MCQ) -- all compulsory, 1 mark each · 1 mark each · 20 of 20 shown

Q1.

Which of the following is not a colligative property of a solution?

(a) Elevation of boiling point
(b) Lowering of vapour pressure
(c) Osmotic pressure
(d) Freezing point

[1]

Q2.

Isotonic solutions have the same:

(a) Normality
(b) Molarity
(c) Osmotic pressure
(d) Formality

[1]

Q3.

The unit of cell constant is:

(a) Ohm^-1 cm^2
(b) cm^-1
(c) Ohm^-1 cm^-1
(d) Ohm^-1 cm^2/ g eq

[1]

Q4.

In a galvanic cell electrons flow from:

(a) Anode to cathode through the external circuit
(b) Anode to cathode through the solution
(c) Cathode to anode through the solution
(d) Cathode to anode through the external circuit

[1]

Q5.

The half life period of a zero order reaction is proportional to:

(a) Initial concentration of the reactant
(b) (Initial concentration of the reactant)^1/2
(c) (Initial concentration of the reactant)^2
(d) (Initial concentration of the reactant)^3

[1]

Q6.

Acid hydrolysis of ethyl acetate is:

(a) Zero order reaction
(b) First order reaction
(c) Second order reaction
(d) Third order reaction

[1]

Page 1 of 7

Q7.

Anomalous electronic configurations in 3d-series are of: (a) Cr and Fe (b) Cr and Cu (c) Cu and Zn (d) Fe and Cu

[1]

Q8.

What is the maximum oxidation state of Mn in its compounds? (a) +4 (b) +5 (c) +6 (d) +7

[1]

Q9.

What is the coordination number of Cobalt in [Co(en)3]Cl3 ? (a) 6 (b) 5 (c) 4 (d) 3

[1]

Q10.

Which of the following ions exhibits optical isomerism? (a) [Cr(NH3)6]3+ (b) [Cr(OX)3]3- (c) [Fe(CN)6]4- (d) [CoF6]3-

[1]

Q11.

Which of the following is known as freon? (a) CCl2F2 (b) CHCl3 (c) CH2F2 (d) CF4

[1]

Q12.

Which of the following is optically active? (a) CH3CH2Cl (b) CH3CHClCH3 (c) CH2ClCH2Cl (d) CH3CH2CHClCH3

[1]

Q13.

The ether C6H5CH2OCH3 when treated with HI produces: (a) CH3OH (b) CH3I (c) C6H5CH2I (d) CH3OCH3

[1]

Q14.

p-nitrophenol is stronger acid than phenol because nitro group is: (a) Electron donating (b) Electron withdrawing (c) Acidic (d) Basic

[1]

Q15.

Which of the following gives silver mirror with Tollen's reagent? (a) Formic acid (b) Acetic acid (c) Acetone (d) Ethyl alcohol

[1]

Q16.

The catalyst used in Rosenmund's reduction is: (a) Zn-Hg (b) Raney-Ni (c) Na in ether (d) Pd-BaSO4

[1]

Q17.

The IUPAC name of (CH3)3C-NH2 is: (a) Trimethyl amine (b) 2-Methylpropan-2-amine (c) 2-Methylpropan-1-amine (d) 2-Methylpropan amine

[1]

Page 2 of 7

Q18.

Aqueous solution of benzene diazonium chloride in presence of dil. H2SO4 is heated to produce: (a) Aniline (b) Benzene (c) Chlorobenzene (d) Phenol

[1]

Q19.

Which of the following is not a pyrimidine base? (a) Adenine (b) Uracil (c) Thymine (d) Cytosine

[1]

Q20.

Which of the following hormones is secreted by pancreas? (a) Testosterone (b) Insulin (c) Cortisone (d) Estrone

[1]

Section B

Short answer -- answer any 7 of 12 printed, 2 marks each · 2 marks each · 12 of 7 shown

Q1.

Calculate the mass of NaOH required to prepare 500 mL of 1.02 N/10 solution.

[2]

Q2.

Represent the cell and calculate the standard emf of the cell having the following cell reaction: 2Cr(s) + 3Cd²+(aq) -> 2Cr³+(aq) + 3Cd(s). Given that, E°(Cr3+/Cr) = -0.73V and E°(Cd2+/Cd) = -0.40V.

[2]

Q3.

The half life period of a first order reaction is 30 min. How much time is required for 75% completion of the reaction? (log 2 = 0.301)

[2]

Q4.

What is a dry cell battery? Give any two examples of the dry cell battery.

[2]

Q5.

The most stable oxidation state of lanthanides is +3. Explain.

[2]

Page 3 of 7

Q6.

[NiCl4]²- ion is tetrahedral and paramagnetic. Explain it by the VBT.

[2]

Q7.

Write any two uses and two environmental effects of dichloromethane.

[2]

Q8.

What happens when CH3CH2OH is oxidised by acidified K2Cr2O7 solution?

[2]

Q9.

What is Urotropine? How is it formed?

[2]

Q10.

What happens when CH3CH2NH2 reacts with NaNO2 and HCl?

[2]

Q11.

What happens when phenol is heated with conc. H2SO4 ?

[2]

Q12.

What are disaccharides? Give any two examples of disaccharides.

[2]

Section C

Short answer -- answer any 7 of 12 printed, 3 marks each · 3 marks each · 12 of 7 shown

Q1.

How is molecular mass of a solute determined from lowering of vapour pressure measurement?

[3]

Page 4 of 7

Q2.

State and explain Kohlrausch's law of independent migration of ions.

[3]

Q3.

Write the Arrhenius equation. Define threshold energy. The activation energy of two reactions are 50 kJ/mol and 25 kJ/mol respectively. Which reaction would take place at a faster rate?

[3]

Q4.

Transition metal compounds and their ions in aqueous solutions look coloured. Explain.

[3]

Q5.

Discuss the splitting of d-orbitals in an octahedral crystal field.

[3]

Q6.

Discuss the mechanism of SN1 reaction of alkyl halides.

[3]

Q7.

How do primary, secondary and tertiary alcohols behave differently when their vapours are passed over reduced Copper at 300°C ?

[3]

Q8.

Write a note on haloform reaction with a typical example.

[3]

Page 5 of 7

Q9.

Define Normality and Molarity. Write the relation between Normality and Molarity.

[3]

Q10.

What is Carbylamine reaction? What is it used for?

[3]

Q11.

What do you mean by denaturation of proteins? Give any two examples.

[3]

Q12.

What happens when CH≡CH reacts with dil. H2SO4 in presence of HgSO4 ? What is the role of HgSO4 in the reaction?

[3]

Section D

Long answer -- answer any 3 of 5 printed, 5 marks each · 5 marks each · 5 of 3 shown

Q1.

What is meant by elevation of boiling point? Boiling point of water is 100°C. Calculate the boiling point of an aqueous solution containing 5 g urea (Mol. Mass = 60) in 100 g water. (Kb for water = 0.52 K.kg.mol^-1) [2+3=5] **OR** Deduce an expression for the rate constant of a zero order reaction. A first order reaction completes 99% in 32 min. Calculate the rate constant of the reaction. [3+2=5]

[5]

Q2.

Define specific conductivity and molar conductivity. Write the relation between them. What is the effect of dilution on the specific conductivity and the molar conductivity? [2+1+2=5] **OR** (a) Write the Nernst equation at 25°C for the electrode reaction, Mⁿ+(aq) + ne- -> M(s). [2] (b) What is an electrochemical cell? Represent a Daniell cell and write its cell reaction. [1+1+1=3]

[5]

Page 6 of 7

Q3.

(a) Discuss the catalytic properties of the first row transition elements. [3] (b) What happens when K2Cr2O7 is heated? [2] **OR** (a) Write the main postulates of Werner's coordination theory. [3] (b) The compound Co(NH3)5CO3Cl has two ionization isomers. Write their structures and give their IUPAC names. [2]

[5]

Q4.

(a) What happens when C6H5Cl is heated with Na in dry ether? What is the name of the reaction? [2+1=3] (b) How is C6H5Cl prepared from benzene by using Lewis acid? [2] **OR** (a) How can you prepare phenol from Chlorobenzene? What is the name of the process? [2+1=3] (b) What happens when phenol is distilled with Zn dust? [2]

[5]

Q5.

(a) How is acetic acid prepared using CH3MgBr? What happens when CH3COOH reacts with C2H5OH in presence of conc. H2SO4 ? [2+2=4] (b) Write two uses of acetic acid. [1] **OR** (a) How is benzene diazonium chloride prepared from aniline? [3] (b) Write the coupling reaction of phenol with benzene diazonium chloride. [2]

[5]

Page 7 of 7