Hydrogen MCQs – Isotopes and Compounds Class 11
Hydrogen MCQs – Isotopes and Compounds (Class 11 Chemistry)
Course: CBSE Class 11 Chemistry – MCQs with Answers and Explanations
Section: Inorganic Chemistry – MCQ Titles
The following 50 Multiple Choice Questions (MCQs) are strictly aligned with the NCERT chapter “Hydrogen”, with special focus on isotopes of hydrogen and its important compounds. The questions are arranged section-wise and include clear, concept-clearing explanations, making them ideal for CBSE Class 11 board exam preparation.
Section A: Introduction and Isotopes of Hydrogen
1. Hydrogen exists in nature mainly in the form of
A. free atoms
B. molecules
C. ions
D. plasma
Answer: B
Explanation: Hydrogen normally exists as a diatomic molecule (H₂).
2. Total number of isotopes of hydrogen are
A. one
B. two
C. three
D. four
Answer: C
Explanation: Protium, deuterium, and tritium are the three isotopes.
3. Protium contains
A. one proton only
B. one proton and one neutron
C. one proton and two neutrons
D. one neutron only
Answer: A
Explanation: Protium (¹H) has one proton and no neutron.
4. Deuterium is also known as
A. light hydrogen
B. heavy hydrogen
C. radioactive hydrogen
D. artificial hydrogen
Answer: B
Explanation: Deuterium (²H or D) contains one neutron, making it heavier.
5. Tritium is
A. stable
B. non-radioactive
C. radioactive
D. artificially radioactive
Answer: C
Explanation: Tritium (³H) is a radioactive isotope.
6. Which isotope of hydrogen is most abundant?
A. Protium
B. Deuterium
C. Tritium
D. Hydronium
Answer: A
Explanation: Protium accounts for about 99.98% of natural hydrogen.
Section B: Uses and Properties of Hydrogen Isotopes
7. Heavy water is represented by
A. H₂O
B. D₂O
C. HDO
D. T₂O
Answer: B
Explanation: Heavy water contains deuterium instead of protium.
8. Heavy water is used in nuclear reactors as
A. fuel
B. coolant
C. moderator
D. absorber
Answer: C
Explanation: It slows down neutrons in nuclear reactions.
9. Tritium is mainly used in
A. hydrogen balloons
B. nuclear fusion reactions
C. hydrogenation reactions
D. batteries
Answer: B
Explanation: Tritium is used in thermonuclear fusion.
10. Deuterium oxide has a higher boiling point than ordinary water because
A. it is ionic
B. it has stronger hydrogen bonding
C. it is heavier
D. it has more oxygen
Answer: B
Explanation: Stronger hydrogen bonding raises boiling point.
Section C: Position of Hydrogen in Periodic Table
11. Hydrogen resembles alkali metals because it
A. forms H⁺ ion
B. is metallic
C. has low electronegativity
D. forms coloured compounds
Answer: A
Explanation: Hydrogen can lose one electron to form H⁺.
12. Hydrogen resembles halogens because it
A. has one electron
B. forms H⁻ ion
C. is diatomic
D. is gaseous
Answer: B
Explanation: Hydrogen can gain one electron like halogens.
13. Due to dual behaviour, hydrogen is placed
A. in Group 1
B. in Group 17
C. separately
D. with noble gases
Answer: C
Explanation: Hydrogen does not fit perfectly in any group.
Section D: Preparation of Hydrogen
14. Hydrogen is prepared in the laboratory by reacting zinc with
A. concentrated nitric acid
B. dilute sulphuric acid
C. concentrated sulphuric acid
D. aqua regia
Answer: B
Explanation: Zn + dilute acid → H₂ gas.
15. Commercial preparation of hydrogen is done by
A. electrolysis of water
B. reaction of metals with acids
C. steam reforming of hydrocarbons
D. photochemical methods
Answer: C
Explanation: Steam reforming of methane is widely used.
16. Electrolysis of water gives
A. only hydrogen
B. hydrogen and oxygen
C. hydrogen and nitrogen
D. oxygen only
Answer: B
Explanation: Hydrogen is liberated at cathode and oxygen at anode.
Section E: Hydrides of Hydrogen
17. Hydrides are compounds of hydrogen with
A. metals only
B. non-metals only
C. metals and non-metals
D. noble gases
Answer: C
Explanation: Hydrogen forms hydrides with many elements.
18. Ionic hydrides are formed by
A. p-block elements
B. transition metals
C. alkali metals
D. noble gases
Answer: C
Explanation: Highly electropositive metals form ionic hydrides.
19. Which is an example of ionic hydride?
A. NH₃
B. CH₄
C. NaH
D. H₂O
Answer: C
Explanation: Sodium hydride contains H⁻ ion.
20. Covalent hydrides are generally formed by
A. s-block elements
B. p-block elements
C. d-block elements
D. f-block elements
Answer: B
Explanation: Non-metals form covalent hydrides.
21. Metallic hydrides are formed by
A. alkali metals
B. alkaline earth metals
C. transition metals
D. halogens
Answer: C
Explanation: Transition metals form interstitial hydrides.
Section F: Water – Structure and Properties
22. Hybridisation of oxygen in water molecule is
A. sp
B. sp²
C. sp³
D. dsp²
Answer: C
Explanation: Oxygen has two bond pairs and two lone pairs.
23. Shape of water molecule is
A. linear
B. tetrahedral
C. bent
D. trigonal planar
Answer: C
Explanation: Lone pair repulsion gives bent shape.
24. Water has maximum density at
A. 0°C
B. 4°C
C. 10°C
D. 100°C
Answer: B
Explanation: Due to hydrogen bonding structure.
25. Hydrogen bonding in water is responsible for
A. low boiling point
B. high boiling point
C. low density of water
D. non-polar nature
Answer: B
Explanation: Hydrogen bonding raises boiling point.
Section G: Hardness of Water
26. Temporary hardness of water is due to
A. sulphates of Ca and Mg
B. chlorides of Ca and Mg
C. bicarbonates of Ca and Mg
D. nitrates of Ca and Mg
Answer: C
Explanation: Bicarbonates cause temporary hardness.
27. Permanent hardness is removed by
A. boiling
B. filtration
C. adding washing soda
D. decantation
Answer: C
Explanation: Na₂CO₃ precipitates Ca²⁺ and Mg²⁺ ions.
Section H: Hydrogen Peroxide (H₂O₂)
28. Oxidation state of oxygen in H₂O₂ is
A. −2
B. −1
C. 0
D. +1
Answer: B
Explanation: Peroxides have oxygen in −1 state.
29. Hydrogen peroxide acts as
A. only oxidising agent
B. only reducing agent
C. both oxidising and reducing agent
D. neutral compound
Answer: C
Explanation: It can accept or donate oxygen.
30. H₂O₂ decomposes to form
A. H₂ and O₂
B. H₂O and O₂
C. H₂ and H₂O
D. O₂ only
Answer: B
Explanation: 2H₂O₂ → 2H₂O + O₂.
31. Which catalyst is used for decomposition of H₂O₂?
A. Zn
B. Cu
C. MnO₂
D. Fe
Answer: C
Explanation: MnO₂ accelerates decomposition.
Section I: Chemical Properties of Hydrogen
32. Hydrogen is a good reducing agent because it
A. donates oxygen
B. accepts oxygen
C. removes oxygen from compounds
D. adds oxygen
Answer: C
Explanation: Hydrogen reduces metal oxides.
33. Which metal oxide is reduced by hydrogen?
A. Na₂O
B. MgO
C. CuO
D. CaO
Answer: C
Explanation: Hydrogen reduces CuO to Cu.
34. Hydrogen burns in oxygen to form
A. H₂O
B. H₂O₂
C. CO₂
D. OH⁻
Answer: A
Explanation: Combustion of hydrogen gives water.
Section J: Uses of Hydrogen and Its Compounds
35. Hydrogen is used in manufacture of
A. ammonia
B. sulphuric acid
C. nitric acid
D. sodium carbonate
Answer: A
Explanation: Haber process uses hydrogen.
36. Hydrogen is used as fuel because it
A. is cheap
B. produces no pollution
C. has high calorific value
D. is easily stored
Answer: C
Explanation: Hydrogen releases large energy on combustion.
37. Heavy water is used in nuclear reactors to
A. absorb neutrons
B. moderate neutrons
C. emit neutrons
D. stop reactions
Answer: B
Explanation: It slows down fast neutrons.
Section K: Conceptual NCERT-Based MCQs
38. Hydrogen shows oxidation state −1 in
A. H₂O
B. NH₃
C. NaH
D. HCl
Answer: C
Explanation: In metal hydrides, hydrogen exists as H⁻.
39. Which hydride is polymeric in nature?
A. CH₄
B. AlH₃
C. NH₃
D. H₂O
Answer: B
Explanation: AlH₃ forms polymeric structures.
40. Hydrogen does not show metallic properties because it
A. is gaseous
B. has small size
C. has high ionisation enthalpy
D. forms covalent bonds
Answer: C
Explanation: High ionisation energy prevents metallic behaviour.
Section L: Application and Higher-Order MCQs
41. Hydrogen economy refers to
A. storage of hydrogen
B. use of hydrogen as clean fuel
C. production of hydrogen
D. purification of hydrogen
Answer: B
Explanation: Hydrogen economy focuses on hydrogen-based energy.
42. Which isotope is used for tracing chemical reactions?
A. Protium
B. Deuterium
C. Tritium
D. Hydronium
Answer: B
Explanation: Deuterium is commonly used as tracer.
43. Which hydride reacts violently with water?
A. CH₄
B. NaH
C. NH₃
D. H₂O
Answer: B
Explanation: Ionic hydrides react vigorously with water.
44. Hydrogen peroxide should be stored in
A. iron container
B. copper container
C. glass container
D. aluminium container
Answer: C
Explanation: Glass prevents catalytic decomposition.
45. Hydrogen is collected over water because it is
A. soluble in water
B. insoluble in water
C. heavier than air
D. toxic
Answer: B
Explanation: Hydrogen is almost insoluble in water.
Section M: Final Conceptual MCQs
46. Hydrogen is considered unique because it
A. is smallest element
B. shows variable oxidation states
C. resembles alkali metals and halogens
D. all of these
Answer: D
Explanation: Hydrogen shows exceptional behaviour.
47. Which compound contains hydrogen bonding?
A. CH₄
B. NH₃
C. H₂S
D. PH₃
Answer: B
Explanation: N–H bonds enable hydrogen bonding.
48. Hydrogen embrittlement occurs due to
A. oxidation
B. corrosion
C. formation of hydrides
D. polymerisation
Answer: C
Explanation: Metal becomes brittle due to hydride formation.
49. Which hydride is amphoteric?
A. NaH
B. CaH₂
C. BeH₂
D. LiH
Answer: C
Explanation: BeH₂ shows both acidic and basic behaviour.
50. Hydrogen is placed separately in periodic table because
A. it is radioactive
B. it is metallic
C. it shows dual behaviour
D. it has high density
Answer: C
Explanation: Hydrogen shows similarity with both Group 1 and 17.
✅ Completion Note
This completes a fully NCERT-aligned, CBSE-standard set of 50 MCQs on Hydrogen (Isotopes and Compounds), ideal for concept clarity, systematic revision, and board exam preparation.