Chemistry · 2019 · Set 56/1/1

CBSE Class 12 Chemistry 2019 — Set 56/1/1

CBSE Class XII Board 2019 · Set 56/1/1

Real board examination⚠ Old pattern · pre-2020 syllabus

Sets

About the 2019 exam: The 2019 exam used CBSE's older pattern — 27 questions for 70 marks, all subjective (no MCQs). All three series (56/1/1, 56/2/1, 56/3/1) are here in full (27/27), each verified against the official CBSE paper. Topics since removed from the syllabus are badged and filterable above.

This paper has 9 questions on a topic removed in CBSE’s 2023-24 syllabus update (each marked Not in syllabus). It’s kept for historical accuracy — the exam really asked it that year — but isn’t in the current syllabus and doesn’t count toward a concept’s importance. Switch to to focus on what’s still examinable.

About this paper

The real Class-12 board examination held in 2019. Every question below is solved the concept-first way. Sample papers are labelled honestly — never shown as a past exam.

Total marks: 70
Questions: 27
Duration: 180 min
Sections: 4

The marks / questions / duration above are the official exam pattern. We currently have 27 of this paper’s questions (100% of the full paper), with 27 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	Very short answer	5	1	5
BSection B	Short answer	7	2	14
CSection C	Short answer	12	3	36
DSection D	Long answer	3	5	15
Total		27		70

The question paper

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

Board Examination

Chemistry

CBSE Class XII Board 2019 · Set 56/1/1

Series/Set: 56/1/1Roll No. ________

Time Allowed: 3 hoursMaximum Marks: 70

General Instructions

This question paper contains 27 questions divided into 4 sections — A, B, C, D.
Section A comprises 5 questions of 1 mark each (Very short answer).
Section B comprises 7 questions of 2 marks each (Short answer).
Section C comprises 12 questions of 3 marks each (Short answer).
Section D comprises 3 questions of 5 marks each (Long answer).

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

Section A

Very short answer · 1 mark each · 5 of 5 shown

Q1.

Out of NaCl and AgCl, which one shows Frenkel defect and why?

⚠ This question is not in the current syllabus — The Solid State (removed 2023-24)

[1]

Q2.

Arrange the following in increasing order of boiling points:

(CH_3)_3N

C_2H_5OH

C_2H_5NH_2

[1]

Q3.

Why are medicines more effective in colloidal state?

(OR)

What is difference between an emulsion and a gel?

⚠ This question is not in the current syllabus — Surface Chemistry (removed 2023-24)

[1]

Q4.

Define ambidient nucleophile with an example.

[1]

Q5.

What is the basic structural difference between glucose and fructose?

(OR)

Write the products obtained after hydrolysis of lactose.

[1]

Page 1 of 5

Section B

Short answer · 2 marks each · 7 of 7 shown

Q1.

Write balanced chemical equations for the following processes: (i) XeF₂ undergoes hydrolysis. (ii) MnO₂ is heated with conc. HCl. OR Arrange the following in order of property indicated for each set: (i) H₂O, H₂S, H₂Se, H₂Te – increasing acidic character (ii) HF, HCl, HBr, HI – decreasing bond enthalpy

⚠ This question is not in the current syllabus — The p-Block Elements (removed 2023-24)

[2]

Q2.

State Raoult’s law for a solution containing volatile components. Write two characteristics of the solution which obeys Raoult’s law at all concentrations.

[2]

Q3.

For a reaction 2H₂O₂ xrightarrow[alkaline medium]I^- 2H₂O + O₂ the proposed mechanism is as given below: (1) H₂O₂ + I^- arrow H₂O + IO^- (slow) (2) H₂O₂ + IO^- arrow H₂O + I^- + O₂ (fast) (i) Write rate law for the reaction. (ii) Write the overall order of reaction. (iii) Out of steps (1) and (2), which one is rate determining step?

[2]

Q4.

When MnO₂ is fused with KOH in the presence of KNO₃ as an oxidizing agent, it gives a dark green compound (A). Compound (A) disproportionates in acidic solution to give purple compound (B). An alkaline solution of compound (B) oxidises KI to compound (C) whereas an acidified solution of compound (B) oxidises KI to (D). Identify (A), (B), (C), and (D).

[2]

Q5.

Write IUPAC name of the complex [Pt(en)₂Cl₂]. Draw structures of geometrical isomers for this complex. OR Using IUPAC norms write the formulae for the following: (i) Hexaamminecobalt(III) sulphate (ii) Potassium trioxalatochromate(III)

[2]

Q6.

Out of [CoF₆]³⁻ and [Co(en)₃]³⁺, which one complex is (i) paramagnetic (ii) more stable (iii) inner orbital complex and (iv) high spin complex (Atomic no. of Co = 27)

[2]

Q7.

Write structures of compounds A and B in each of the following reactions: (i) 4-ethylphenol (a benzene ring bearing a -CH₂CH₃ group and a -OH group para to it) xrightarrowKMnO₄ - KOH A xrightarrowH₃O^+ B (ii) Cyclohexanol (a cyclohexane ring bearing a -OH group) xrightarrowCrO₃ A xrightarrowH₂N-NH-CONH₂ B

[2]

Page 2 of 5

Section C

Short answer · 3 marks each · 12 of 12 shown

Q1.

The decomposition of NH₃ on platinum surface is zero order reaction. If rate constant (k) is 4 × 10⁻³ Ms⁻¹, how long will it take to reduce the initial concentration of NH₃ from 0.1 M to 0.064 M?

[3]

Q2.

(i) What is the role of activated charcoal in a gas mask? (ii) A colloidal sol is prepared by the method shown in the figure: FeCl₃ solution is added dropwise into NaOH solution taken in a test tube. What is the charge on the hydrated ferric oxide colloidal particles formed in the test tube? How is the sol represented? (iii) How does chemisorption vary with temperature?

⚠ This question is not in the current syllabus — Surface Chemistry (removed 2023-24)

[3]

Q3.

An element crystallizes in fcc lattice with a cell edge of 300 pm. The density of the element is 10.8 gcm⁻³. Calculate the number of atoms in 108 g of the element.

⚠ This question is not in the current syllabus — The Solid State (removed 2023-24)

[3]

Q4.

A 4% solution (w/w) of sucrose (M = 342 gmol⁻¹) in water has a freezing point of 271.15 K. Calculate the freezing point of 5% glucose (M = 180 gmol⁻¹) in water. (Given: Freezing point of pure water = 273.15 K)

[3]

Q5.

(a) Name the method of refining which is (i) used to obtain semiconductor of high purity, (ii) used to obtain low boiling metal. (b) Write chemical reactions taking place in the extraction of copper from Cu₂S.

⚠ This question is not in the current syllabus — Metallurgy (removed 2023-24)

[3]

Q6.

Give reasons for the following: (i) Transition elements and their compounds act as catalysts. (ii) E^° value for (Mn²⁺|Mn) is negative whereas for (Cu²⁺|Cu) is positive. (iii) Actinoids show irregularities in their electronic configuration.

[3]

Page 3 of 5

Q7.

Write the structures of monomers used for getting the following polymers: (i) Nylon-6,6 (ii) Glyptal (iii) Buna-S OR (i) Is -[CH₂-undersetCH₃CH]ₙ- a homopolymer or copolymer? Give reason. (ii) Write the monomers of the following polymer: a repeating unit built on a 1,3,5-triazine ring (a six-membered ring of alternating C and N atoms) linked through -NH- and -NH-CH₂- groups and carrying an -NH- substituent, i.e. -[HN-C₃N₃(NH)-NH-CH₂]ₙ- (iii) What is the role of Sulphur in vulcanization of rubber?

⚠ This question is not in the current syllabus — Polymers (removed 2023-24)

[3]

Q8.

(i) What type of drug is used in sleeping pills? (ii) What type of detergents are used in toothpastes? (iii) Why the use of alitame as artificial sweetener is not recommended? OR Define the following terms with a suitable example in each: (i) Broad-spectrum antibiotics (ii) Disinfectants (iii) Cationic detergents

⚠ This question is not in the current syllabus — Chemistry in Everyday Life (removed 2023-24)

[3]

Q9.

(i) Out of (CH₃)₃C-Br and (CH₃)₃C-I, which one is more reactive towards SN1 and why? (ii) Write the product formed when p-nitrochlorobenzene is heated with aqueous NaOH at 443 K followed by acidification. (iii) Why dextro and laevo–rotatory isomers of Butan-2-ol are difficult to separate by fractional distillation?

[3]

Q10.

An aromatic compound ‘A’ on heating with Br₂ and KOH forms a compound ‘B’ of molecular formula C₆H₇N which on reacting with CHCl₃ and alcoholic KOH produces a foul smelling compound ‘C’. Write the structures and IUPAC names of compounds A, B and C.

[3]

Q11.

Complete the following reactions: (i) Benzaldehyde, C₆H₅CHO xrightarrowNaCN/HCl (ii) (C₆H₅CH₂)₂Cd + 2CH₃COCl arrow (iii) (CH₃)₂CH-COOH xrightarrow[(ii)H₂O](i)Br₂/RedP₄ OR Write chemical equations for the following reactions: (i) Propanone is treated with dilute Ba(OH)₂. (ii) Acetophenone is treated with Zn(Hg)/Conc. HCl. (iii) Benzoyl chloride is hydrogenated in presence of Pd/BaSO₄.

[3]

Q12.

Differentiate between the following: (i) Amylose and Amylopectin (ii) Peptide linkage and Glycosidic linkage (iii) Fibrous proteins and Globular proteins OR Write chemical reactions to show that open structure of D-glucose contains the following: (i) Straight chain (ii) Five alcohol groups (iii) Aldehyde as carbonyl group

[3]

Page 4 of 5

Section D

Long answer · 5 marks each · 3 of 3 shown

Q1.

Ecell for the given redox reaction is 2.71 V Mg(s) + Cu²⁺(0.01M) arrow Mg²⁺(0.001M) + Cu(s) Calculate Ecell for the reaction. Write the direction of flow of current when an external opposite potential applied is (i) less than 2.71 V and (ii) greater than 2.71 V OR (a) A steady current of 2 amperes was passed through two electrolytic cells X and Y connected in series containing electrolytes FeSO₄ and ZnSO₄ until 2.8 g of Fe deposited at the cathode of cell X. How long did the current flow? Calculate the mass of Zn deposited at the cathode of cell Y. (Molar mass: Fe = 56 gmol⁻¹, Zn = 65.3 gmol⁻¹, 1F = 96500 Cmol⁻¹) (b) In the plot of molar conductivity (Lambdam, y-axis) vs square root of concentration (c1/2, x-axis), two curves are obtained for electrolytes A and B: curve A stays high and decreases only slightly and almost linearly with c1/2, whereas curve B lies lower and rises steeply as c1/2 approaches zero. Answer the following: (i) Predict the nature of electrolytes A and B. (ii) What happens on extrapolation of Lambdam to concentration approaching zero for electrolytes A and B?

[5]

Q2.

(a) How do you convert the following: (i) Phenol to Anisole (ii) Ethanol to Propan-2-ol (b) Write mechanism of the following reaction: C₂H₅OH xrightarrow[443K]H₂SO₄ CH₂=CH₂ + H₂O (c) Why phenol undergoes electrophilic substitution more easily than benzene? OR (a) Account for the following: (i) o-nitrophenol is more steam volatile than p-nitrophenol. (ii) t-butyl chloride on heating with sodium methoxide gives 2-methylpropene instead of t-butylmethylether. (b) Write the reaction involved in the following: (i) Reimer-Tiemann reaction (ii) Friedal-Crafts Alkylation of Phenol (c) Give simple chemical test to distinguish between Ethanol and Phenol.

[5]

Q3.

(a) Give reasons for the following: (i) Sulphur in vapour state shows paramagnetic behaviour. (ii) N-N bond is weaker than P-P bond. (iii) Ozone is thermodynamically less stable than oxygen. (b) Write the name of gas released when Cu is added to (i) dilute HNO₃ and (ii) conc. HNO₃ OR (a) (i) Write the disproportionation reaction of H₃PO₃. (ii) Draw the structure of XeF₄. (b) Account for the following: (i) Although Fluorine has less negative electron gain enthalpy yet F₂ is strong oxidizing agent. (ii) Acidic character decreases from N₂O₃ to Bi₂O₃ in group 15. (c) Write a chemical reaction to test sulphur dioxide gas. Write chemical equation involved.

⚠ This question is not in the current syllabus — The p-Block Elements (removed 2023-24)

[5]

Page 5 of 5