Chemistry · Class 12 Science

Mizoram Mbse 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.

2021–2025
Years of papers: 5
Total Papers: 5
Real Board Papers: 0
Sample papers: 178
Real-paper Q & A: 0
Sample-paper Q & A

Real board-paper questions available, by year

36 Q2025complete

37 Q2024complete

35 Q2023complete

35 Q2022complete

35 Q2021complete

Mizoram Board of School Education HSSLC 2025 · Set ANNUAL

Real board examination

About this paper

The real Class-12 board examination held in 2025. Every question below is solved the concept-first way. Sample papers are labelled honestly — never shown as a past exam.

Total marks: 70
Questions: 36
Duration: 180 min
Sections: 4

The marks / questions / duration above are the official exam pattern. We currently have 36 of this paper’s questions (100% of the full paper), with 36 fully solved. Questions we couldn’t yet extract or verify are held — never shown as complete.

Sections & marks

Section	Type	Questions	Marks each	Total
MCQ (1 mark)Section MCQ (1 mark)	compulsory	14	1	14
Short answer (2 marks)Section Short answer (2 marks)	compulsory	16	2	32
Long answer (4 marks, internal choice)Section Long answer (4 marks, internal choice)	compulsory	3	4	12
Long answer (4 marks)Section Long answer (4 marks)	compulsory	3	4	12
Total		36		70

The question paper

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

Board Examination

Chemistry

Mizoram Board of School Education HSSLC 2025 · Set ANNUAL

Series/Set: ANNUALRoll No. ________

Time Allowed: 3 hoursMaximum Marks: 70

General Instructions

This question paper contains 36 questions divided into 4 sections — MCQ (1 mark), Short answer (2 marks), Long answer (4 marks, internal choice), Long answer (4 marks).
Section MCQ (1 mark) comprises 14 questions of 1 mark each (compulsory).
Section Short answer (2 marks) comprises 16 questions of 2 marks each (compulsory).
Section Long answer (4 marks, internal choice) comprises 3 questions of 4 marks each (compulsory).
Section Long answer (4 marks) comprises 3 questions of 4 marks each (compulsory).

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

Section A

Q1.

The IUPAC name of CH₂OH-CHOH-CH₂OH (a 3-carbon chain with an -OH group on each carbon, drawn vertically as CH₂OH / CHOH / CH₂OH) is –

(i) Propane-1,3-diol
(ii) Propane-1,2-diol
(iii) Propane-1,2,3-triol
(iv) Glycerol

[1]

Q2.

The half life of a first order reaction is 69.3 s. Its rate constant is –

(i) 10⁻² s⁻¹
(ii) 10⁻⁴ s⁻¹
(iii) 10 s⁻¹
(iv) 10² s⁻¹

[1]

Q3.

The co-ordination compounds [Co(NH₃)₆][Cr(CN)₆] and [Cr(NH₃)₆][Co(CN)₆] are examples of –

(i) Ionisation Isomerism
(ii) Linkage Isomerism
(iii) Coordination Isomerism
(iv) Geometrical Isomerism

[1]

Q4.

For solutes which do not undergo any association or dissociation in solution, the Van't Hoff factor

(i) will be –
(i) less than 1
(ii) more than 1
(iii) equal to 1
(iv) zero

[1]

Q5.

The carbon atom attached to halogen in haloalkane is –

(i) sp² hybridised
(ii) sp³ hybridised
(iii) sp hybridised
(iv) None of these

[1]

Q6.

Which of the following is most reactive towards nucleophilic substitution reaction –

(i) C₆H₅Cl
(ii) CH₂=CHCl
(iii) ClCH₂CH=CH₂
(iv) CH₃-CH=CHCl

[1]

Page 1 of 6

Q7.

Iodoform test is not given by – (i) Pentan-2-one (ii) Pentan-3-one (iii) Ethanol (iv) Ethanal

[1]

Q8.

Which of the following will have the highest conductivity at 298 K ? (i) 0.01 M HCl solution (ii) 0.1 M HCl solution (iii) 0.01 M CH₃COOH solution (iv) 0.1 M CH₃COOH solution

[1]

Q9.

Which of the following is least basic ? (i) (CH₃)₂NH (ii) NH₃ (iii) C₆H₅NH₂ (iv) (CH₃)₃N

[1]

Q10.

The IUPAC name of the compound CH₃-CH=CH-C(=O)-CH₂-COOH (a 6-carbon chain: COOH as C1, CH₂ as C2, the ketone C=O as C3, CH=CH as C4-C5, CH₃ as C6) is – (i) 2-oxo-hex-1-enoic acid (ii) 3-oxo-hex-2-enoic acid (iii) 1-formyl-hex-4-en-3-one (iv) 3-oxo-hex-4-enoic acid

[1]

Q11.

Aromatic primary amines and aliphatic primary amines can be distinguished by – (i) Hinsberg's test (ii) Tollen's test (iii) Azo dye test (iv) Litmus test

[1]

Q12.

During dehydration of alcohols to alkenes by heating with Conc. H₂SO₄, the initial step is – (i) Protonation of alcohol (ii) Formation of carbocation (iii) Elimination of water (iv) Formation of an ester

[1]

Q13.

Which element does not show variable oxidation state ? (i) Vanadium (ii) Iron (iii) Mercury (iv) Scandium

[1]

Q14.

Nucleic acids are polymers of – (i) Nucleotides (ii) Saccharic acid (iii) Ascorbic acid (iv) Adipic acid

[1]

Section B

Q1.

Explain the phenomenon of weakness and discomfort in breathing at high altitudes with the help of Henry's law.

[2]

Page 2 of 6

Q2.

Is it possible to measure the voltage of an isolated half reaction ? Give reasons.

[2]

Q3.

The molar conductivities at infinite dilution for NaI, CH₃COONa and (CH₃COO)₂Mg are 126.9, 91.0 and 187.8 S cm² mol⁻¹ respectively at 25°C. What is the molar conductivity of MgI₂ at infinite dilution ?

[2]

Q4.

Which of the two Fe²⁺ or Fe³⁺ has larger magnetic moment and why ?

[2]

Q5.

Write a short note on Mendius reaction and give one example.

[2]

Q6.

Write the reaction mechanism when propan-1-ol is treated with Conc. H₂SO₄ at 443 K.

[2]

Q7.

Identify A and B in the following reaction : [Benzene ring] --(Conc.HNO₃/Conc.H₂SO₄)--> A --(Fe,HCl / reduction)--> B

[2]

Q8.

Consider the reaction 2A + B → Product. When concentration of B alone was doubled, half-life time does not change. When concentration of A alone was doubled, the rate increases by two times. What is the order of reaction and unit of rate constant, k ?

[2]

Q9.

To a 0.02 mole of [Co(NH₃)₅Br]Cl₂ solution, excess AgNO₃ solution was added. Calculate the number of moles of AgCl precipitated.

[2]

Page 3 of 6

Q10.

Write short note on Williamson's synthesis and give one example.

[2]

Q11.

Why are vinyl halides less reactive than alkyl halides ?

[2]

Q12.

Out of SN1 and SN2, which reaction occurs with : (a) inversion of configuration (b) racemization

[2]

Q13.

Why are ketones less reactive than aldehydes towards nucleophilic reactions ?

[2]

Q14.

ClCH₂COOH is a stronger acid than CH₃COOH. Explain.

[2]

Q15.

Differentiate between enzymes and co-enzymes.

[2]

Q16.

An organic compound X has molecular formula C₅H₁₀O. It does not reduce Fehling's solution but it gives positive Iodoform test. What are the possible structures of X ?

[2]

Page 4 of 6

Section C

Q1.

A solution containing 10.2 g of glycerine per litre is found to be isotonic with 2% solution of glucose. Calculate the molar mass of glycerine. (Molar mass of glucose = 180 g mol⁻¹) **OR** A solution of sucrose (Molar mass = 342 g mol⁻¹) is prepared by dissolving 70 g of it per litre of solution. What is the osmotic pressure at 27°C ? (R = 0.082 L bar K⁻¹ mol⁻¹)

[4]

Q2.

A first order decomposition reaction takes 40 minutes for 30% decomposition. Calculate its t½ value. **OR** The rate constant of a first order reaction becomes 5 times when the temperature is raised from 77°C to 127°C. Calculate the activation energy of the reaction. (R = 8.314 J K⁻¹ mol⁻¹)

[4]

Q3.

Write Nernst equation and calculate emf of the cell at 298 K. Mg(s) / Mg²⁺(0.001M) || Cu²⁺(0.0001M)/Cu(s) Given E°(Mg²⁺/Mg) = −2.37V ; E°(Cu²⁺/Cu) = +0.34V **OR** What is the value of Ecell at equilibrium ? Calculate the equilibrium constant for the following cell reaction. 4Br⁻ + O₂ + 4H⁺ → 2Br₂ + 2H₂O Given that E°Cell = 0.16 V. (1+3=4)

[4]

Q4.

Give the IUPAC name of [Fe(CN)₆]⁴⁻. Using valence bond theory, predict the type of hybridisation, geometry and magnetic behaviour of [Fe(H₂O)₆]³⁺ ion. (1+3=4)

[4]

Q5.

What are carbohydrates ? Write three important functions of carbohydrates. (1+3=4)

[4]

Page 5 of 6

Q6.

When a chromite ore (A) is fused with Na₂CO₃ in presence of air, a yellow solution of compound (B) is obtained which on treatment with H₂SO₄ give compound (C). When compound (C) is treated with KCl, orange crystals of compound (D) crystallizes out. Identify the compounds A to D and also write the reaction.

[4]

Page 6 of 6