Case Study Based MCQs – CBSE Class 11 Chemistry
Case Study Based MCQs – CBSE Class 11 Chemistry
Course: CBSE Class 11 Chemistry – MCQs with Answers and Explanations
Section: Exam-Oriented & Practice-Based Titles
The following 50 Case Study–Based Multiple Choice Questions (MCQs) are strictly prepared as per the NCERT Class 11 Chemistry syllabus and follow the CBSE competency-based pattern. Each case study is followed by application-oriented questions with detailed, concept-clearing explanations, making them ideal for board exams, school assessments, and practice-based learning.
Case Study 1: Mole Concept and Stoichiometry
A student dissolves 5.3 g of sodium carbonate (Na₂CO₃) in water to prepare a solution.
1. Molar mass of Na₂CO₃ is
A. 84 g mol⁻¹
B. 96 g mol⁻¹
C. 106 g mol⁻¹
D. 112 g mol⁻¹
Answer: C
Explanation: Na₂CO₃ = (23×2) + 12 + (16×3) = 106 g mol⁻¹.
2. Number of moles of Na₂CO₃ taken is
A. 0.05
B. 0.1
C. 0.5
D. 1
Answer: A
Explanation: Moles = 5.3 ÷ 106 = 0.05 mol.
3. Number of carbonate ions present is
A. 0.05 mol
B. 0.1 mol
C. 0.15 mol
D. 1 mol
Answer: A
Explanation: One mole of Na₂CO₃ gives one mole of CO₃²⁻.
Case Study 2: Atomic Structure
Hydrogen spectrum shows discrete lines when excited gas emits light.
4. These lines are due to
A. random electron motion
B. continuous energy levels
C. transition between fixed energy levels
D. nuclear reactions
Answer: C
Explanation: Electrons jump between quantised energy levels.
5. The model explaining hydrogen spectrum is
A. Rutherford model
B. Thomson model
C. Bohr model
D. Quantum mechanical model
Answer: C
Explanation: Bohr successfully explained hydrogen spectrum.
6. Energy emitted during transition is released as
A. heat
B. particle
C. photon
D. electron
Answer: C
Explanation: Energy difference is emitted as photon.
Case Study 3: Periodic Trends
Across a period, atomic size decreases and ionisation energy increases.
7. Atomic size decreases because
A. electrons increase
B. shielding increases
C. nuclear charge increases
D. mass increases
Answer: C
Explanation: Increased nuclear charge attracts electrons strongly.
8. Ionisation enthalpy increases because
A. electrons are loosely held
B. atomic size decreases
C. shielding increases
D. atomic mass increases
Answer: B
Explanation: Smaller size makes electron removal difficult.
9. Most electronegative element in a period is
A. alkali metal
B. alkaline earth metal
C. halogen
D. noble gas
Answer: C
Explanation: Halogens strongly attract electrons.
Case Study 4: Chemical Bonding
Methane has tetrahedral geometry with equal bond angles.
10. Hybridisation of carbon in methane is
A. sp
B. sp²
C. sp³
D. dsp²
Answer: C
Explanation: Four equivalent sp³ orbitals form.
11. Bond angle in methane is
A. 90°
B. 104.5°
C. 109.5°
D. 120°
Answer: C
Explanation: Tetrahedral angle is 109.5°.
12. Geometry of methane is explained by
A. VBT
B. VSEPR theory
C. MOT
D. kinetic theory
Answer: B
Explanation: VSEPR predicts shape based on repulsions.
Case Study 5: States of Matter
Real gases deviate from ideal behaviour at high pressure.
13. Deviation occurs due to
A. zero volume
B. intermolecular attraction
C. absence of collisions
D. ideal behaviour
Answer: B
Explanation: Intermolecular forces become significant.
14. At high temperature, gases behave ideally because
A. pressure decreases
B. volume decreases
C. molecular motion increases
D. forces increase
Answer: C
Explanation: High kinetic energy overcomes attractions.
15. Ideal gas equation is
A. PV = nRT
B. P + V = RT
C. PV = RT
D. P/T = constant
Answer: A
Explanation: Ideal gas law includes amount of gas.
Case Study 6: Thermodynamics
A reaction absorbs heat from surroundings.
16. Such a reaction is
A. exothermic
B. endothermic
C. neutral
D. spontaneous
Answer: B
Explanation: Heat absorption defines endothermic reaction.
17. Enthalpy change for this reaction is
A. negative
B. zero
C. positive
D. infinite
Answer: C
Explanation: Endothermic reactions have +ΔH.
18. First law of thermodynamics is based on
A. entropy
B. spontaneity
C. conservation of energy
D. equilibrium
Answer: C
Explanation: Energy is conserved.
Case Study 7: Equilibrium
At equilibrium, concentrations remain constant.
19. Equilibrium is
A. static
B. dynamic
C. irreversible
D. complete
Answer: B
Explanation: Forward and backward reactions continue.
20. Increasing temperature for exothermic reaction
A. increases yield
B. decreases yield
C. no effect
D. stops reaction
Answer: B
Explanation: Heat acts as product.
21. Equilibrium constant depends on
A. concentration
B. pressure
C. temperature
D. catalyst
Answer: C
Explanation: K depends only on temperature.
Case Study 8: Redox Reactions
Zinc reacts with copper sulphate solution.
22. Zinc undergoes
A. reduction
B. oxidation
C. hydrolysis
D. neutralisation
Answer: B
Explanation: Zinc loses electrons.
23. Copper ion undergoes
A. oxidation
B. reduction
C. displacement
D. ionisation
Answer: B
Explanation: Cu²⁺ gains electrons.
24. Zinc acts as
A. oxidising agent
B. reducing agent
C. catalyst
D. electrolyte
Answer: B
Explanation: It causes reduction of Cu²⁺.
Case Study 9: s-Block Elements
Sodium reacts vigorously with water.
25. Sodium is stored under kerosene because it
A. is radioactive
B. reacts with air and water
C. melts easily
D. is poisonous
Answer: B
Explanation: Sodium is highly reactive.
26. Sodium belongs to
A. Group 2
B. Group 13
C. Group 1
D. Group 17
Answer: C
Explanation: Sodium is an alkali metal.
27. Nature of NaOH formed is
A. acidic
B. neutral
C. basic
D. amphoteric
Answer: C
Explanation: Sodium hydroxide is a strong base.
Case Study 10: p-Block Elements
Carbon shows extensive catenation.
28. Catenation refers to
A. bond polarity
B. chain formation
C. ion formation
D. isomerism
Answer: B
Explanation: Self-linking property of carbon.
29. Maximum catenation is shown by
A. silicon
B. carbon
C. tin
D. lead
Answer: B
Explanation: Strong C–C bonds.
30. Carbon is placed in Group
A. 13
B. 14
C. 15
D. 16
Answer: B
Explanation: Carbon family is Group 14.
Case Study 11: Organic Chemistry Basics
Organic compounds contain carbon.
31. Organic chemistry deals mainly with
A. metals
B. carbon compounds
C. salts
D. acids only
Answer: B
Explanation: Carbon forms vast number of compounds.
32. Homologous series differ by
A. functional group
B. molecular formula
C. –CH₂– group
D. name
Answer: C
Explanation: Successive members differ by –CH₂–.
33. Functional group determines
A. molecular mass
B. chemical properties
C. density
D. boiling point only
Answer: B
Explanation: Reactivity depends on functional group.
Case Study 12: Hydrocarbons
Ethene undergoes addition reactions.
34. Ethene is
A. alkane
B. alkene
C. alkyne
D. aromatic
Answer: B
Explanation: Presence of double bond.
35. Addition reaction occurs due to
A. sigma bond
B. pi bond
C. hydrogen bond
D. ionic bond
Answer: B
Explanation: Pi bond is weaker and reactive.
36. Hybridisation of carbon in ethene is
A. sp
B. sp²
C. sp³
D. dsp²
Answer: B
Explanation: Double bond involves sp² hybridisation.
Case Study 13: Environmental Chemistry
Excess fertiliser use pollutes water bodies.
37. This leads to
A. corrosion
B. eutrophication
C. acid rain
D. smog
Answer: B
Explanation: Nutrient enrichment causes algal bloom.
38. Main greenhouse gas is
A. O₂
B. N₂
C. CO₂
D. H₂
Answer: C
Explanation: CO₂ traps heat.
39. Ozone layer protects Earth from
A. infrared rays
B. X-rays
C. UV rays
D. visible light
Answer: C
Explanation: Ozone absorbs harmful UV radiation.
Case Study 14: Chemistry in Everyday Life
Antacids relieve acidity.
40. Antacids are
A. acidic
B. basic
C. neutral
D. oxidising
Answer: B
Explanation: They neutralise acid.
41. Example of antacid is
A. NaCl
B. Mg(OH)₂
C. HCl
D. NH₄Cl
Answer: B
Explanation: Magnesium hydroxide is basic.
42. Antibiotics are used to
A. reduce pain
B. reduce fever
C. kill bacteria
D. improve digestion
Answer: C
Explanation: Antibiotics destroy bacteria.
Case Study 15: General Exam-Oriented Concepts
MCQ practice improves exam performance.
43. Limiting reagent determines
A. rate of reaction
B. amount of product
C. equilibrium constant
D. temperature
Answer: B
Explanation: It limits maximum yield.
44. Mole fraction is
A. temperature dependent
B. volume dependent
C. dimensionless
D. mass dependent
Answer: C
Explanation: It is a ratio of moles.
45. pH less than 7 indicates
A. neutral solution
B. basic solution
C. acidic solution
D. buffer
Answer: C
Explanation: Acids have pH < 7.
46. Diamond is hard because
A. it is ionic
B. it has hydrogen bonds
C. strong covalent network
D. metallic bonding
Answer: C
Explanation: sp³ covalent network.
47. Hydrogen bonding increases
A. volatility
B. boiling point
C. density decrease
D. acidity only
Answer: B
Explanation: Extra energy required to break bonds.
48. Oxidation means
A. gain of electrons
B. loss of electrons
C. gain of neutrons
D. loss of protons
Answer: B
Explanation: Oxidation involves electron loss.
49. Noble gases are inert because
A. they are heavy
B. they have filled valence shells
C. they are metals
D. they lack electrons
Answer: B
Explanation: Stable electronic configuration.
50. Case study questions mainly test
A. memory
B. rote learning
C. application of concepts
D. handwriting
Answer: C
Explanation: Case studies focus on analytical and application skills.
✅ Completion Note
This completes a fully NCERT-aligned, CBSE-standard set of 50 Case Study–Based MCQs for Class 11 Chemistry, designed to strengthen concept application, analytical thinking, and exam readiness.