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Chemistry · 2026 All years Show answers Download PDF PDF with answers
Roll No.
Q.P. Code 56/1/1

Chemistry (Theory)

CBSE Class XII Board Examination 2026

Time allowed: 3 hoursMaximum Marks: 70

General Instructions:

  1. The paper has 33 questions in five sections (A to E); all of them must be answered.
  2. Section A: Q1–16, multiple choice (Q13–16 Assertion-Reason), 1 mark each.
  3. Section B: Q17–21, very short answer, 2 marks each.
  4. Section C: Q22–28, short answer, 3 marks each.
  5. Section D: Q29–30, case-based, 4 marks each.
  6. Section E: Q31–33, long answer, 5 marks each.
  7. There is no overall choice, but some questions in Sections B to E offer an internal choice (OR). Calculators are not allowed.

SECTION A

Q1–16 are multiple choice questions of 1 mark each (Q13–16 are Assertion-Reason).
1.
Four graphs are shown. Which one is characteristic of a first order reaction?
(A) t½ plotted against initial concentration [R]₀ is a straight line rising from the origin.
(B) t½ plotted against [R]₀ is a horizontal straight line.
(C) Rate plotted against concentration is a horizontal straight line.
(D) Rate plotted against concentration is a curve that falls steeply and then levels off.
  1. (A) t½ vs [R]₀: straight line rising from origin
  2. (B) t½ vs [R]₀: horizontal line
  3. (C) Rate vs concentration: horizontal line
  4. (D) Rate vs concentration: falling curve
1
2.
Among the following aqueous solutions, which one freezes at the lowest temperature?
  1. (A) 0.1 M glucose
  2. (B) 0.1 M CaCl₂
  3. (C) 0.1 M KCl
  4. (D) 0.1 M urea
1
3.
Identify the element that is NOT regarded as a transition metal.
  1. (A) Sc
  2. (B) Ag
  3. (C) Hg
  4. (D) Cu
1
4.
Which expression gives the fraction of molecules that have energy equal to or greater than the activation energy Ea?
  1. (A) \( +\dfrac{E_a}{RT} \)
  2. (B) \( e^{-E_a/RT} \)
  3. (C) \( -\dfrac{E_a}{RT} \)
  4. (D) \( e^{+E_a/RT} \)
1
5.
An aqueous solution of CuCl₂ is electrolysed using platinum electrodes. What is observed?
  1. (A) Copper deposits at the anode
  2. (B) H₂ gas is evolved at the cathode
  3. (C) O₂ gas is evolved at the anode
  4. (D) Cl₂ gas is evolved at the anode
1
6.
Aspirin is prepared by acetylating which compound?
  1. (A) Phenol
  2. (B) Salicylaldehyde
  3. (C) 2-Hydroxybenzoic acid
  4. (D) Benzoic acid
1
7.
What is the secondary valency of cobalt in the complex ion [Co(NH₃)₅(NO₂)]²⁺?
  1. (A) 5
  2. (B) 1
  3. (C) 4
  4. (D) 6
1
8.
When phenol is treated with dilute nitric acid at low temperature (about 298 K), the product is:
  1. (A) 2,4,6-trinitrophenol
  2. (B) o-nitrophenol only
  3. (C) p-nitrophenol only
  4. (D) a mixture of o- and p-nitrophenol
1
9.
Pick the statement that is NOT correct for a pair of enantiomers.
  1. (A) Their chemical reactivity (towards achiral reagents) is the same.
  2. (B) Their specific rotation is the same.
  3. (C) Their melting/boiling points are the same.
  4. (D) Their refractive index is the same.
1
10.
Direct nitration of aniline (with nitrating mixture) gives which product distribution?
  1. (A) 51% ortho, 47% para, 2% meta
  2. (B) 51% meta, 47% ortho, 2% para
  3. (C) 51% para, 47% meta, 2% ortho
  4. (D) 51% ortho, 47% meta, 2% para
1
11.
Which of these amines has the lowest pKb (i.e. is the strongest base)?
  1. (A) C₆H₅–N(CH₃)₂
  2. (B) C₆H₅–NH(CH₃)
  3. (C) C₆H₅–NH₂
  4. (D) p-O₂N–C₆H₄–NH₂ (4-nitroaniline)
1
12.
Lack of which vitamin leads to increased fragility of red blood cells and weakness of muscles?
  1. (A) Vitamin A
  2. (B) Vitamin K
  3. (C) Vitamin E
  4. (D) Vitamin D
1
13.
Assertion (A): The two components of an azeotropic mixture cannot be separated by fractional distillation.
Reason (R): An azeotrope boils at a constant temperature, and its liquid and vapour have the same composition.
  1. (A) Both A and R are true, and R correctly explains A.
  2. (B) Both A and R are true, but R does not explain A.
  3. (C) A is true, but R is false.
  4. (D) A is false, but R is true.
1
14.
Assertion (A): In phenols the –OH group sends the incoming electrophile to the meta position.
Reason (R): The –OH group of phenol activates the benzene ring for electrophilic substitution.
  1. (A) Both A and R are true, and R correctly explains A.
  2. (B) Both A and R are true, but R does not explain A.
  3. (C) A is true, but R is false.
  4. (D) A is false, but R is true.
1
15.
Assertion (A): Actinoids exhibit a wide range of oxidation states.
Reason (R): Actinoids are radioactive.
  1. (A) Both A and R are true, and R correctly explains A.
  2. (B) Both A and R are true, but R does not explain A.
  3. (C) A is true, but R is false.
  4. (D) A is false, but R is true.
1
16.
Assertion (A): Glucose pentaacetate does not react with hydroxylamine (H₂N–OH).
Reason (R): This shows that glucose has a free –CHO group.
  1. (A) Both A and R are true, and R correctly explains A.
  2. (B) Both A and R are true, but R does not explain A.
  3. (C) A is true, but R is false.
  4. (D) A is false, but R is true.
1

SECTION B

Q17–21 are very short answer questions of 2 marks each.
17.
A mixture of phenol and aniline deviates from Raoult's law. State the type of deviation with reason. How does the boiling point of the mixture compare with that expected?
2
18.
Give two reasons why aryl halides (haloarenes) are much less reactive than alkyl halides towards nucleophilic substitution.
2
19.
Give the IUPAC names of:
(i) [Ag(NH₃)₂][Ag(CN)₂]
(ii) K₃[Fe(C₂O₄)₃]
OR
(i) Suggest a chemical test to show that [Co(NH₃)₅SO₄]Cl and [Co(NH₃)₅Cl]SO₄ are ionisation isomers.
(ii) What is the chelate effect? Give one example.
2
20.
Distinguish between:
(i) a peptide linkage and a glycosidic linkage
(ii) essential and non-essential amino acids
2
21.
The reaction 2A + B → 2C occurs in a single (elementary) step. If the volume of the reaction vessel is reduced to one-third of its original value, how does the rate change? Does the order of the reaction change?
2

SECTION C

Q22–28 are short answer questions of 3 marks each.
22.
The gas-phase decomposition C₂H₅Cl(g) → C₂H₄(g) + HCl(g) is first order. The total pressure was 0.30 atm at t = 0 s and 0.50 atm at t = 30 s. Find the rate constant. (log 3 = 0.48)
3
23.
Answer:
(i) Why is the equilibrium constant Kc linked to E°cell and not to Ecell?
(ii) Metals A and B have standard electrode potentials −0.24 V and +0.80 V respectively. Which of them can displace hydrogen from dilute H₂SO₄?
(iii) Write the reaction taking place in a lead storage battery while it is being charged.
OR
What kind of battery is the mercury cell? Why is it better than a dry cell? Write the overall cell reaction of the mercury cell.
3
24.
0.61 g of benzoic acid (M = 122 g mol⁻¹) is dissolved in 5 g of CS₂, in which it dimerises to the extent of 88%. Find the boiling point of the solution. (Boiling point of CS₂ = 46.2 °C, Kb = 2.3 K kg mol⁻¹)
3
25.
Write the reactions of D-glucose with:
(a) HI (on prolonged heating)
(b) bromine water
(c) concentrated HNO₃
3
26.
Explain:
(a) Carboxylic acids boil at higher temperatures than alcohols of similar molar mass.
(b) The α-hydrogens of aldehydes and ketones are acidic.
(c) Ammonia and its derivatives do not add to the carbonyl group in a strongly acidic medium.
3
27.
Write the chemical reaction for each:
(a) Reimer–Tiemann reaction
(b) Kolbe's reaction
(c) Friedel–Crafts acylation of anisole
3
28.
A compound X (C₄H₉Br) gives an alcohol with aqueous KOH, and the rate depends only on [X]. An optically active isomer Y of X reacts with aqueous KOH at a rate that depends on both [Y] and [KOH].
(a) Give the structures of X and Y.
(b) Which of X and Y would undergo racemisation, and why?
(c) Which one gives a product with inversion of configuration, and why?
3

SECTION D

Q29–30 are case-based questions of 4 (2 + 1 + 1) marks each, with an internal choice.
29.
Amines are basic and form salts with acids; aliphatic amines are stronger bases than NH₃ while aryl amines are weaker. 1° and 2° amines are acylated by acid chlorides; aryl amines are very reactive towards electrophiles (o/p substitution). Hinsberg's reagent distinguishes 1°, 2° and 3° amines, and arenediazonium salts are used to make aryl halides, nitriles, phenols and arenes.
(a) (i) In water, why is CH₃NH₂ a stronger base than (CH₃)₃N?
(ii) Give structures of A and B: CH₃CONH₂ —(NaOBr)→ A —(C₆H₅COCl, base)→ B.
(b) A compound X (C₃H₉N) gives with Hinsberg's reagent a product that is insoluble in alkali. Identify X.
(c) Why is the –NH₂ group of aniline acetylated before nitration?
OR
(b)
How would you convert aniline into benzonitrile?
4
30.
Valence bond theory explains the formation, magnetism and shape of complexes. Crystal field theory treats ligands as point charges that remove the degeneracy of the metal d orbitals; different electron arrangements result in strong and weak fields.
(a) In an octahedral field, which d orbitals are raised in energy as the ligands approach? Give the reason.
(b) Using CFT, write the d-electron configuration of the central ion in (i) [CoF₆]³⁻ (ii) [Co(NH₃)₆]³⁺. (Co = 27)
(c) Both [NiCl₄]²⁻ and [Ni(CO)₄] are tetrahedral, but the first is paramagnetic and the second diamagnetic. Why? (Ni = 28)
OR
(c)
State the hybridisation and magnetic nature of [Fe(CN)₆]³⁻. (Fe = 26)
4

SECTION E

Q31–33 are long answer questions of 5 marks each.
31.
(i) An organic compound X has molecular formula C₅H₁₀O. Draw X if it:
(I) gives a negative Tollens' test but a positive iodoform test;
(II) gives neither Tollens' nor iodoform test but undergoes aldol condensation;
(III) undergoes Cannizzaro reaction.
(ii) How can each of these be converted into benzoic acid? (I) Acetophenone (II) Ethylbenzene
OR
Answer briefly:
(i) Draw the 2,4-dinitrophenylhydrazone of benzaldehyde.
(ii) Arrange in increasing order of reactivity towards HCN: di-tert-butyl ketone, acetaldehyde, acetone.
(iii) Give a simple chemical test to tell benzoic acid from ethyl benzoate.
(iv) Name the reagent that converts ethanenitrile into ethanal.
(v) Give the structure of X: cyclohexanol —(CrO₃)→ X.
5
32.
(i) Standard electrode potentials E°(M²⁺/M) in volts are: V −1.18, Cr −0.91, Mn −1.18, Fe −0.44, Co −0.28, Ni −0.25, Cu +0.34. Using these:
(I) Why do the values show an irregular trend?
(II) Why is E°(Cu²⁺/Cu) unusually positive?
(III) Why is E°(Mn²⁺/Mn) highly negative?
(ii) Write ionic equations for the oxidation of I⁻ by KMnO₄ in (a) acidic and (b) neutral/faintly alkaline solution.
OR
Answer:
(i) Name a lanthanoid that shows (I) the +4 oxidation state (II) the +2 oxidation state.
(ii) Why are transition metals good catalysts?
(iii) Why does Cr have a higher melting point than Mn?
(iv) What happens when an acidic solution of KMnO₄ is kept for some time? Write the equation and name the type of reaction.
5
33.
Find the emf and ΔG of this cell at 298 K:
Mg(s) | Mg²⁺(0.01 M) || Ag⁺(0.001 M) | Ag(s)
Given E°(Mg²⁺/Mg) = −2.37 V, E°(Ag⁺/Ag) = +0.80 V, 1 F = 96500 C mol⁻¹, log 10 = 1.
OR
For the cell reaction 2AgCl(s) + H₂(g, 0.4 atm) → 2Ag(s) + 2H⁺(0.1 M) + 2Cl⁻(0.2 M), ΔG° = −43500 J mol⁻¹. Find the emf of the cell at 25 °C. (log 10 = 1, 1 F = 96500 C mol⁻¹)
5
— END —
Questions restated from the CBSE Class XII Board Examination 2026 (set 56/1/1) for practice. Reading passages and map items are described, not reproduced.