NCERT Based Chemistry MCQs with Answers – Class 11
NCERT Based Chemistry MCQs with Answers – Class 11
Course: CBSE Class 11 Chemistry – MCQs with Answers and Explanations
Section: Exam-Oriented & Practice-Based Titles
The following 50 Multiple Choice Questions (MCQs) are strictly based on the NCERT syllabus and cover Physical, Inorganic, and Organic Chemistry concepts taught in Class 11. The questions are arranged section-wise, focusing on exam-oriented practice, concept clarity, and CBSE board exam readiness.
Section A: Basic Concepts & Mole Concept
1. The SI unit of amount of substance is
A. gram
B. mole
C. kilogram
D. atomic mass unit
Answer: B
Explanation: Mole is the SI unit for amount of substance.
2. Number of particles in one mole of a substance is
A. 6.022 × 10²²
B. 6.022 × 10²³
C. 3.011 × 10²³
D. 1.66 × 10⁻²⁴
Answer: B
Explanation: Avogadro number equals 6.022 × 10²³.
3. The law of conservation of mass was proposed by
A. Dalton
B. Lavoisier
C. Avogadro
D. Boyle
Answer: B
Explanation: It states mass is neither created nor destroyed.
4. Which quantity changes with temperature?
A. Molality
B. Mole fraction
C. Molarity
D. Mass percentage
Answer: C
Explanation: Molarity depends on volume, which varies with temperature.
5. Empirical formula represents
A. actual number of atoms
B. simplest whole-number ratio of atoms
C. molecular mass
D. total atoms in molecule
Answer: B
Explanation: Empirical formula gives simplest ratio.
Section B: Atomic Structure
6. The maximum number of electrons in an orbital is
A. 1
B. 2
C. 8
D. 18
Answer: B
Explanation: Pauli’s exclusion principle allows maximum two electrons.
7. Which quantum number determines the shape of an orbital?
A. Principal
B. Azimuthal
C. Magnetic
D. Spin
Answer: B
Explanation: Azimuthal quantum number defines orbital shape.
8. Cathode rays consist of
A. protons
B. neutrons
C. electrons
D. alpha particles
Answer: C
Explanation: Cathode rays are streams of electrons.
9. The Bohr model failed to explain spectra of
A. hydrogen
B. helium
C. hydrogen-like atoms
D. ions
Answer: B
Explanation: Bohr model applies only to single-electron systems.
10. Aufbau principle is related to
A. electron spin
B. electron pairing
C. order of filling of orbitals
D. orbital shapes
Answer: C
Explanation: It explains the sequence of orbital filling.
Section C: Periodicity and Chemical Bonding
11. Periodic properties are the functions of
A. atomic mass
B. atomic volume
C. atomic number
D. density
Answer: C
Explanation: Modern periodic law is based on atomic number.
12. Atomic radius generally decreases across a period due to
A. shielding effect
B. increase in shells
C. increase in nuclear charge
D. decrease in electrons
Answer: C
Explanation: Greater nuclear charge pulls electrons closer.
13. VSEPR theory is used to predict
A. bond energy
B. molecular shape
C. bond length
D. polarity
Answer: B
Explanation: It predicts geometry based on electron pair repulsion.
14. Hybridisation of carbon in methane is
A. sp
B. sp²
C. sp³
D. dsp²
Answer: C
Explanation: Four equivalent sp³ orbitals form tetrahedral shape.
15. Strongest repulsion occurs between
A. bond pair–bond pair
B. bond pair–lone pair
C. lone pair–lone pair
D. all equal
Answer: C
Explanation: Lone pairs occupy more space.
Section D: States of Matter & Thermodynamics
16. Real gases deviate from ideal behaviour at
A. low pressure, high temperature
B. high pressure, low temperature
C. normal conditions
D. zero kelvin
Answer: B
Explanation: Intermolecular forces become significant.
17. The value of universal gas constant (R) is
A. 0.082 L atm K⁻¹ mol⁻¹
B. 8.314 J K⁻¹ mol⁻¹
C. both A and B
D. none
Answer: C
Explanation: R has different units in different systems.
18. First law of thermodynamics is based on
A. entropy
B. enthalpy
C. conservation of energy
D. spontaneity
Answer: C
Explanation: Energy can neither be created nor destroyed.
19. Enthalpy is defined as
A. U − PV
B. U + PV
C. U / V
D. P / V
Answer: B
Explanation: H = U + PV.
20. Endothermic reactions have
A. negative ΔH
B. positive ΔH
C. zero ΔH
D. infinite ΔH
Answer: B
Explanation: Heat is absorbed, so ΔH is positive.
Section E: Equilibrium and Redox Reactions
21. Chemical equilibrium is
A. static
B. irreversible
C. dynamic
D. complete
Answer: C
Explanation: Forward and backward reactions occur simultaneously.
22. For an exothermic reaction, increase in temperature
A. increases equilibrium constant
B. decreases equilibrium constant
C. does not affect equilibrium
D. reverses reaction
Answer: B
Explanation: Le Chatelier’s principle applies.
23. pH value of a neutral solution at 25°C is
A. 0
B. 7
C. 14
D. 1
Answer: B
Explanation: Neutral solutions have pH = 7.
24. Oxidation is defined as
A. gain of electrons
B. loss of electrons
C. gain of protons
D. loss of neutrons
Answer: B
Explanation: Oxidation involves loss of electrons.
25. An oxidising agent
A. gets oxidised
B. loses electrons
C. gains electrons
D. remains unchanged
Answer: C
Explanation: Oxidising agent itself gets reduced.
Section F: s-Block and p-Block Elements
26. Alkali metals have general configuration
A. ns²
B. ns¹
C. ns²np¹
D. ns²np⁶
Answer: B
Explanation: One valence electron makes them highly reactive.
27. Lithium shows anomalous behaviour due to
A. large size
B. high electronegativity
C. small size and high polarising power
D. metallic nature
Answer: C
Explanation: Lithium differs from rest of Group 1.
28. Boron compounds are mainly
A. ionic
B. covalent
C. metallic
D. coordinate
Answer: B
Explanation: Boron forms covalent compounds due to high ionisation energy.
29. Most stable oxidation state of aluminium is
A. +1
B. +2
C. +3
D. +4
Answer: C
Explanation: Aluminium shows +3 oxidation state.
30. Carbon shows maximum catenation because
A. it is metallic
B. C–C bond is strong
C. it has large size
D. it forms ionic bonds
Answer: B
Explanation: Strong C–C bonds allow long chains.
Section G: Organic Chemistry Basics
31. Organic compounds mainly contain
A. hydrogen and oxygen
B. carbon and hydrogen
C. nitrogen and oxygen
D. metals
Answer: B
Explanation: Organic chemistry is chemistry of carbon compounds.
32. Homologous series differ by
A. one carbon atom
B. –CH₂– unit
C. functional group
D. molecular mass only
Answer: B
Explanation: Each successive member differs by –CH₂–.
33. Functional group determines
A. physical state
B. chemical properties
C. molecular mass
D. density
Answer: B
Explanation: Functional group controls reactivity.
34. IUPAC nomenclature is based on
A. trivial names
B. systematic rules
C. local names
D. common usage
Answer: B
Explanation: IUPAC provides systematic naming.
35. Saturated hydrocarbons contain
A. single bonds only
B. double bonds
C. triple bonds
D. aromatic rings
Answer: A
Explanation: Alkanes contain only single bonds.
Section H: Environmental & Everyday Chemistry
36. Ozone depletion is mainly caused by
A. CO₂
B. SO₂
C. CFCs
D. NO₂
Answer: C
Explanation: CFCs release chlorine radicals.
37. Greenhouse gas responsible for global warming is
A. oxygen
B. nitrogen
C. carbon dioxide
D. helium
Answer: C
Explanation: CO₂ traps heat in atmosphere.
38. Detergents are preferred over soaps in hard water because they
A. are cheaper
B. do not form scum
C. are acidic
D. contain sodium
Answer: B
Explanation: Detergents do not react with Ca²⁺ and Mg²⁺ ions.
39. Antacids are used to
A. increase acidity
B. neutralise excess acid
C. cause digestion
D. kill bacteria
Answer: B
Explanation: They neutralise stomach acid.
40. Medicines that kill bacteria are called
A. analgesics
B. antipyretics
C. antibiotics
D. antiseptics
Answer: C
Explanation: Antibiotics destroy bacteria.
Section I: High-Order & Exam-Oriented MCQs
41. Limiting reagent determines
A. reaction rate
B. equilibrium constant
C. amount of product formed
D. temperature change
Answer: C
Explanation: It limits maximum yield.
42. Mole fraction is
A. temperature dependent
B. pressure dependent
C. dimensionless
D. mass dependent
Answer: C
Explanation: It is a ratio of moles.
43. Hybridisation concept explains
A. atomic mass
B. molecular shape
C. density
D. atomic number
Answer: B
Explanation: Hybrid orbitals decide geometry.
44. Most electronegative element is
A. oxygen
B. chlorine
C. nitrogen
D. fluorine
Answer: D
Explanation: Fluorine has highest electronegativity.
45. The strongest bond among C–C, C=C and C≡C is
A. single bond
B. double bond
C. triple bond
D. hydrogen bond
Answer: C
Explanation: Triple bond has highest bond energy.
46. pH less than 7 indicates
A. neutral solution
B. basic solution
C. acidic solution
D. buffer solution
Answer: C
Explanation: Acids have pH < 7.
47. Which property remains constant in isotopes?
A. atomic mass
B. atomic number
C. number of neutrons
D. density
Answer: B
Explanation: Isotopes have same atomic number.
48. Which compound shows hydrogen bonding?
A. CH₄
B. NH₃
C. PH₃
D. H₂S
Answer: B
Explanation: N–H bond enables hydrogen bonding.
49. The hardest allotrope of carbon is
A. graphite
B. diamond
C. charcoal
D. coke
Answer: B
Explanation: Strong sp³ network makes diamond hard.
50. The best method for last-minute revision is
A. reading textbooks
B. solving numericals
C. practising MCQs
D. writing notes
Answer: C
Explanation: MCQs test concepts quickly and effectively.
✅ Completion Note
This completes a fully NCERT-aligned, exam-oriented set of 50 MCQs covering all major units of CBSE Class 11 Chemistry, ideal for practice, revision, and board exam preparation.