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Hydrogen

78 Short Q&A for JEE Advanced • NCERT Class 11

Class 11 JEE Advanced

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78 Short Q&A for Hydrogen

Part 1: Basic Properties and Structure
1. Q1: What is the electron configuration of hydrogen?
   A: 1s¹.
2. Q2: What is the atomic number of hydrogen?
   A: 1.
3. Q3: Hydrogen is placed in which group in the periodic table?
   A: Group 1.
4. Q4: Is hydrogen a metal or non-metal?
   A: Non-metal.
5. Q5: Hydrogen shows properties of which groups?
   A: Alkali metals and halogens in some cases.
6. Q6: What is the molecular orbital configuration of H₂?
   A: (σ_1s)² only bonding orbital filled.
7. Q7: What is the bond order of H₂?
   A: 1.
8. Q8: What is the bond length of the H₂ molecule?
   A: Approximately 0.74 Å.
9. Q9: What type of bond is present in H₂ molecule?
   A: A sigma covalent bond formed by overlap of 1s orbitals.
10. Q10: What is the bond dissociation energy of H₂?
    A: Approximately 436 kJ/mol.
11. Q11: What is polarity of H–H bond?
    A: Nonpolar covalent bond.
12. Q12: What type of energy is released when H–H bond breaks?
    A: Bond dissociation energy (endothermic).
13. Q13: Why does hydrogen have high ionization energy?
    A: Small size and one proton binding one electron strongly.
14. Q14: What is the electron affinity of hydrogen?
    A: 72.8 kJ/mol.
15. Q15: What is the structure of the hydrogen molecule in the ground state?
    A: Both electrons are paired in the bonding sigma orbital.
16. Q16: What is the melting point of hydrogen?
    A: −259.2 °C.
17. Q17: What is the boiling point of hydrogen?
    A: −252.87 °C.
18. Q18: What is the color of hydrogen gas?
    A: Colorless.
19. Q19: What is the smell of hydrogen?
    A: Odorless.
20. Q20: What is the flammability of hydrogen?
    A: Highly flammable.
21. Q21: What is the molecular weight of hydrogen?
    A: 2 g/mol.
22. Q22: What is the density of hydrogen?
    A: 0.0899 g/L at STP.
23. Q23: What is the Brownian motion of hydrogen?
    A: Visible rapid random motion due to small mass.
Part 2: Isotopes and Ortho/Para Hydrogen
24. Q24: What are the isotopes of hydrogen?
    A: Protium (¹H), deuterium (²H), and tritium (³H).
25. Q25: What is the most abundant isotope of hydrogen?
    A: Protium (¹H).
26. Q26: Which hydrogen isotope is radioactive?
    A: Tritium (³H).
27. Q27: How is tritium produced?
    A: By neutron bombardment of lithium or heavy water in nuclear reactors.
28. Q28: What is the main use of deuterium?
    A: Heavy water (D₂O) used as a moderator in nuclear reactors.
29. Q29: Which isotope of hydrogen is used as a tracer in chemical reactions?
    A: Deuterium.
30. Q30: What is the use of tritium?
    A: As a tracer in biochemical research and nuclear fusion fuel.
31. Q31: Which hydrogen isotope is used in nuclear fusion?
    A: Deuterium (²H) and Tritium (³H).
32. Q32: Does hydrogen have allotropes?
    A: Yes, ortho and para hydrogen.
33. Q33: What is ortho and para hydrogen?
    A: Ortho hydrogen has parallel nuclear spins; para has antiparallel spins.
34. Q34: What is the electron spin state of ortho-hydrogen?
    A: Spins are parallel (triplet state equivalent for nuclei).
35. Q35: What is the electron spin state of para-hydrogen?
    A: Spins are antiparallel (singlet state equivalent for nuclei).
36. Q36: Which form of hydrogen is paramagnetic?
    A: Ortho-hydrogen.
37. Q37: Which is more stable, ortho-hydrogen or para-hydrogen?
    A: Para-hydrogen is more stable at low temperatures.
38. Q38: Why is para-hydrogen more stable?
    A: Lower energy spin state with antiparallel spins.
39. Q39: What happens to ortho-hydrogen at very low temperatures?
    A: It converts to para-hydrogen.
40. Q40: What is the nuclear spin of hydrogen?
    A: 1/2.
Part 3: Hydrides and Hydrogen Bonding
41. Q41: What is a hydride ion?
    A: H⁻, hydrogen with an extra electron.
42. Q42: What are hydrides?
    A: Binary compounds of hydrogen with metals or non-metals.
43. Q43: How do you classify hydrides?
    A: Ionic, covalent, and interstitial (metallic) hydrides.
44. Q44: Give an example of an ionic hydride.
    A: NaH, CaH₂.
45. Q45: What is the characteristic of an ionic hydride?
    A: Formed with active metals; conducts electricity in the molten state.
46. Q46: Give an example of a covalent hydride.
    A: CH₄, NH₃, H₂O.
47. Q47: What do the hydrides of nitrogen and phosphorus belong to?
    A: Covalent hydrides.
48. Q48: Give an example of an interstitial hydride.
    A: TiH₂.
49. Q49: Which hydrides are good reducing agents?
    A: Ionic hydrides.
50. Q50: Which hydride of group 1 is more covalent (or less ionic)?
    A: Lithium hydride.
51. Q51: What is the oxidation state of hydrogen in metal hydrides?
    A: −1.
52. Q52: What are hydrogen bonds?
    A: Attractive forces between hydrogen attached to an electronegative atom and a lone pair of another electronegative atom.
53. Q53: In which compounds is hydrogen bonding the strongest?
    A: HF molecules.
54. Q54: What is the effect of hydrogen bonding on the boiling point of water?
    A: It raises the boiling point significantly.
Part 4: Production and Reactions
55. Q55: How is hydrogen prepared in the laboratory?
    A: Reaction of granulated Zn with dilute H₂SO₄.
56. Q56: Which compound is the source of hydrogen used in labs?
    A: Zn + dilute acid.
57. Q57: What is the industrial method of hydrogen production?
    A: Water gas reaction and steam methane reforming.
58. Q58: How is hydrogen detected in the laboratory?
    A: Burning produces a 'pop' sound.
59. Q59: How is hydrogen stored industrially?
    A: In high-pressure cylinders or in metal hydrides.
60. Q60: What is the reaction of hydrogen with oxygen?
    A: 2H₂ + O₂ → 2H₂O (highly exothermic).
61. Q61: What is the hydrogen oxidation state in H₂O?
    A: +1.
62. Q62: What is the reaction of hydrogen with nitrogen?
    A: Forms ammonia under Haber’s process.
63. Q63: What is the role of hydrogen in ammonia synthesis?
    A: Reacts with nitrogen to form NH₃.
64. Q64: State the Haber process conditions.
    A: 200 atm, 450-500 °C, Fe catalyst.
65. Q65: What is the role of the catalyst in the Haber process?
    A: Lowers the activation energy for N₂ fixation.
66. Q66: What is the effect of temperature on equilibrium in the Haber process?
    A: High temperature favors backward decomposition (exothermic forward).
67. Q67: How does hydrogen react with halogens?
    A: Forms hydrogen halides (HX).
68. Q68: What happens if H₂ is mixed with chlorine and exposed to light?
    A: It forms hydrogen chloride via a radical chain reaction.
69. Q69: What is the acid strength order among hydrogen halides?
    A: HI > HBr > HCl > HF.
70. Q70: Which hydrogen halide is the most reactive?
    A: HF bonds are strong, but HF is least reactive as an acid (HI is most acidic).
71. Q71: Can H₂ act as a reducing agent?
    A: Yes, it reduces many metal oxides to metals.
72. Q72: Why does hydrogen exhibit both oxidizing and reducing properties?
    A: It can either lose one electron (reducing) or gain one electron (oxidizing) easily.
Part 5: Applications and Miscellaneous
73. Q73: What is the main industrial use of hydrogen?
    A: Ammonia production, hydrogenation of oils, and petroleum refining.
74. Q74: What is the important use of hydrogen in the petroleum industry?
    A: Hydrocracking and hydrogenation.
75. Q75: What is used as fuel in hydrogen fuel cells?
    A: Pure hydrogen gas and oxygen.
76. Q76: What is the standard hydrogen electrode (SHE)?
    A: An electrode based on hydrogen gas, acting as the zero reference for redox potentials.
77. Q77: What is the standard electrode potential of hydrogen?
    A: 0 V (by definition).
78. Q78: What is the greenhouse effect of hydrogen?
    A: Negligible compared to other gases.

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