Hydrogen Practice

Take 5 chapter-wise practice tests of 25 questions each on Hydrogen for NEET with +4/-1 scoring, answer review, and concise explanations.

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NEET Chemistry - Chapter 16

Hydrogen Practice Tests

5 original practice tests, 25 questions each, NEET 4/-1 marking, and answer review after submission.

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Position
1. Hydrogen is placed with alkali metals mainly because it has:
- A. one valence electron (Correct)
- B. high density
- C. metallic lattice
- D. two valence electrons
Explanation: Its configuration is 1s$^1$.
Position
2. Hydrogen also resembles halogens because it can:
- A. gain one electron to form H$^-$ (Correct)
- B. form only cations
- C. show d-block character
- D. have zero ionization enthalpy
Explanation: Hydrogen can complete its duplet by gaining one electron.
Isotopes
3. The isotope of hydrogen containing one proton and one neutron is:
- A. deuterium (Correct)
- B. protium
- C. tritium
- D. positronium
Explanation: Deuterium is $^2$H or D.
Isotopes
4. The radioactive isotope of hydrogen is:
- A. tritium (Correct)
- B. protium
- C. deuterium
- D. hydride
Explanation: Tritium is $^3$H and radioactive.
Preparation
5. Hydrogen is commonly prepared in the lab by action of dilute acid on:
- A. zinc (Correct)
- B. copper
- C. silver
- D. gold
Explanation: Zinc reacts readily with dilute acids to liberate H$_2$.
Occurrence
6. In the universe, hydrogen is the:
- A. most abundant element (Correct)
- B. least reactive metal
- C. heaviest non-metal
- D. rarest gas
Explanation: Hydrogen dominates stellar matter.
Molecular form
7. Hydrogen exists as:
- A. H$_2$ molecule (Correct)
- B. H atom only
- C. H$_3$ cluster
- D. monatomic gas
Explanation: Hydrogen is diatomic under normal conditions.
Hydrides
8. Ionic hydrides are generally formed by:
- A. alkali and alkaline earth metals (Correct)
- B. halogens only
- C. transition metals only
- D. noble gases
Explanation: Highly electropositive metals form saline hydrides.
Hydrides
9. Covalent hydrides are commonly formed by:
- A. p-block elements (Correct)
- B. alkali metals only
- C. lanthanoids only
- D. actinoids only
Explanation: Many p-block elements form molecular hydrides.
Hydrides
10. The hydride containing H as H$^-$ is called:
- A. ionic hydride (Correct)
- B. metallic hydride
- C. interstitial hydride
- D. protic solvent
Explanation: Hydrogen exists as hydride ion in saline hydrides.
Water
11. Heavy water is:
- A. D$_2$O (Correct)
- B. H$_2$O$_2$
- C. T$_2$O
- D. HD
Explanation: Heavy water contains deuterium instead of protium.
Water
12. Hardness of water due to bicarbonates is called:
- A. temporary hardness (Correct)
- B. permanent hardness
- C. saline hardness
- D. metallic hardness
Explanation: Bicarbonate hardness can be removed by boiling.
Water
13. Permanent hardness of water is mainly due to:
- A. chlorides and sulfates of Ca and Mg (Correct)
- B. bicarbonates only
- C. sodium salts only
- D. dissolved oxygen
Explanation: These salts do not decompose on boiling.
Peroxide
14. Hydrogen peroxide has molecular formula:
- A. H$_2$O$_2$ (Correct)
- B. HO$_2$
- C. H$_2$O
- D. H$_2$
Explanation: Hydrogen peroxide contains a peroxide linkage.
Peroxide
15. Oxidation state of oxygen in H$_2$O$_2$ is:
- A. -1 (Correct)
- B. -2
- C. 0
- D. +1
Explanation: Peroxides contain oxygen in -1 state.
Peroxide use
16. Hydrogen peroxide acts as a bleaching agent because it is a:
- A. strong oxidising agent (Correct)
- B. strong reducing agent only
- C. neutral salt
- D. metallic catalyst
Explanation: It releases nascent oxygen in many reactions.
Reducing nature
17. Hydrogen peroxide can act as a reducing agent toward:
- A. strong oxidising agents like KMnO$_4$ (Correct)
- B. alkali metals
- C. noble gases
- D. water
Explanation: H$_2$O$_2$ shows dual redox behavior.
Structure
18. The O-O bond present in hydrogen peroxide is a:
- A. single bond (Correct)
- B. double bond
- C. triple bond
- D. coordinate bond
Explanation: Peroxide has a single O-O linkage.
Water properties
19. Ice floats on water because ice has:
- A. lower density than liquid water (Correct)
- B. higher molecular mass
- C. ionic bonding
- D. greater conductivity
Explanation: Open hydrogen-bonded structure lowers density.
Hydrogen bond
20. High boiling point of water is due to:
- A. extensive hydrogen bonding (Correct)
- B. high atomic mass of hydrogen
- C. metallic bonding
- D. large number of neutrons
Explanation: Intermolecular H-bonding is strong in water.
Dual nature
21. Hydrogen is unique because it resembles both:
- A. alkali metals and halogens (Correct)
- B. noble gases and lanthanoids
- C. alkaline earth metals and actinoids
- D. transition metals and metalloids
Explanation: Its single electron and ability to gain one electron create this duality.
Hydrides
22. Electron-deficient hydrides such as diborane are called:
- A. electron-deficient covalent hydrides (Correct)
- B. saline hydrides
- C. interstitial hydrides
- D. stoichiometric salts
Explanation: They have multicenter bonding and too few electrons for classical structures.
Water treatment
23. Temporary hardness of water can be removed by:
- A. boiling (Correct)
- B. adding NaCl
- C. cooling only
- D. distillation with acid
Explanation: Bicarbonates decompose on heating.
Water treatment
24. Calgon method removes hardness using:
- A. sodium hexametaphosphate (Correct)
- B. alum
- C. bleaching powder
- D. hydrogen peroxide
Explanation: Calgon complexes Ca$^{2+}$ and Mg$^{2+}$ ions.
Hydrogen logic
25. A safe scoring route in this chapter is to separate questions into isotopes, hydrides, water chemistry, and:
- A. hydrogen peroxide behavior (Correct)
- B. electrode potential
- C. unit-cell defects
- D. radioactivity series
Explanation: That split covers most NEET asks cleanly.
Position
26. Hydrogen is placed with alkali metals mainly because it has:
- A. one valence electron (Correct)
- B. high density
- C. metallic lattice
- D. two valence electrons
Explanation: Its configuration is 1s$^1$.
Position
27. Hydrogen also resembles halogens because it can:
- A. gain one electron to form H$^-$ (Correct)
- B. form only cations
- C. show d-block character
- D. have zero ionization enthalpy
Explanation: Hydrogen can complete its duplet by gaining one electron.
Isotopes
28. The isotope of hydrogen containing one proton and one neutron is:
- A. deuterium (Correct)
- B. protium
- C. tritium
- D. positronium
Explanation: Deuterium is $^2$H or D.
Isotopes
29. The radioactive isotope of hydrogen is:
- A. tritium (Correct)
- B. protium
- C. deuterium
- D. hydride
Explanation: Tritium is $^3$H and radioactive.
Preparation
30. Hydrogen is commonly prepared in the lab by action of dilute acid on:
- A. zinc (Correct)
- B. copper
- C. silver
- D. gold
Explanation: Zinc reacts readily with dilute acids to liberate H$_2$.
Occurrence
31. In the universe, hydrogen is the:
- A. most abundant element (Correct)
- B. least reactive metal
- C. heaviest non-metal
- D. rarest gas
Explanation: Hydrogen dominates stellar matter.
Molecular form
32. Hydrogen exists as:
- A. H$_2$ molecule (Correct)
- B. H atom only
- C. H$_3$ cluster
- D. monatomic gas
Explanation: Hydrogen is diatomic under normal conditions.
Hydrides
33. Ionic hydrides are generally formed by:
- A. alkali and alkaline earth metals (Correct)
- B. halogens only
- C. transition metals only
- D. noble gases
Explanation: Highly electropositive metals form saline hydrides.
Hydrides
34. Covalent hydrides are commonly formed by:
- A. p-block elements (Correct)
- B. alkali metals only
- C. lanthanoids only
- D. actinoids only
Explanation: Many p-block elements form molecular hydrides.
Hydrides
35. The hydride containing H as H$^-$ is called:
- A. ionic hydride (Correct)
- B. metallic hydride
- C. interstitial hydride
- D. protic solvent
Explanation: Hydrogen exists as hydride ion in saline hydrides.
Water
36. Heavy water is:
- A. D$_2$O (Correct)
- B. H$_2$O$_2$
- C. T$_2$O
- D. HD
Explanation: Heavy water contains deuterium instead of protium.
Water
37. Hardness of water due to bicarbonates is called:
- A. temporary hardness (Correct)
- B. permanent hardness
- C. saline hardness
- D. metallic hardness
Explanation: Bicarbonate hardness can be removed by boiling.
Water
38. Permanent hardness of water is mainly due to:
- A. chlorides and sulfates of Ca and Mg (Correct)
- B. bicarbonates only
- C. sodium salts only
- D. dissolved oxygen
Explanation: These salts do not decompose on boiling.
Peroxide
39. Hydrogen peroxide has molecular formula:
- A. H$_2$O$_2$ (Correct)
- B. HO$_2$
- C. H$_2$O
- D. H$_2$
Explanation: Hydrogen peroxide contains a peroxide linkage.
Peroxide
40. Oxidation state of oxygen in H$_2$O$_2$ is:
- A. -1 (Correct)
- B. -2
- C. 0
- D. +1
Explanation: Peroxides contain oxygen in -1 state.
Peroxide use
41. Hydrogen peroxide acts as a bleaching agent because it is a:
- A. strong oxidising agent (Correct)
- B. strong reducing agent only
- C. neutral salt
- D. metallic catalyst
Explanation: It releases nascent oxygen in many reactions.
Reducing nature
42. Hydrogen peroxide can act as a reducing agent toward:
- A. strong oxidising agents like KMnO$_4$ (Correct)
- B. alkali metals
- C. noble gases
- D. water
Explanation: H$_2$O$_2$ shows dual redox behavior.
Structure
43. The O-O bond present in hydrogen peroxide is a:
- A. single bond (Correct)
- B. double bond
- C. triple bond
- D. coordinate bond
Explanation: Peroxide has a single O-O linkage.
Water properties
44. Ice floats on water because ice has:
- A. lower density than liquid water (Correct)
- B. higher molecular mass
- C. ionic bonding
- D. greater conductivity
Explanation: Open hydrogen-bonded structure lowers density.
Hydrogen bond
45. High boiling point of water is due to:
- A. extensive hydrogen bonding (Correct)
- B. high atomic mass of hydrogen
- C. metallic bonding
- D. large number of neutrons
Explanation: Intermolecular H-bonding is strong in water.
Dual nature
46. Hydrogen is unique because it resembles both:
- A. alkali metals and halogens (Correct)
- B. noble gases and lanthanoids
- C. alkaline earth metals and actinoids
- D. transition metals and metalloids
Explanation: Its single electron and ability to gain one electron create this duality.
Hydrides
47. Electron-deficient hydrides such as diborane are called:
- A. electron-deficient covalent hydrides (Correct)
- B. saline hydrides
- C. interstitial hydrides
- D. stoichiometric salts
Explanation: They have multicenter bonding and too few electrons for classical structures.
Water treatment
48. Temporary hardness of water can be removed by:
- A. boiling (Correct)
- B. adding NaCl
- C. cooling only
- D. distillation with acid
Explanation: Bicarbonates decompose on heating.
Water treatment
49. Calgon method removes hardness using:
- A. sodium hexametaphosphate (Correct)
- B. alum
- C. bleaching powder
- D. hydrogen peroxide
Explanation: Calgon complexes Ca$^{2+}$ and Mg$^{2+}$ ions.
Hydrogen logic
50. A safe scoring route in this chapter is to separate questions into isotopes, hydrides, water chemistry, and:
- A. hydrogen peroxide behavior (Correct)
- B. electrode potential
- C. unit-cell defects
- D. radioactivity series
Explanation: That split covers most NEET asks cleanly.
Position
51. Hydrogen is placed with alkali metals mainly because it has:
- A. one valence electron (Correct)
- B. high density
- C. metallic lattice
- D. two valence electrons
Explanation: Its configuration is 1s$^1$.
Position
52. Hydrogen also resembles halogens because it can:
- A. gain one electron to form H$^-$ (Correct)
- B. form only cations
- C. show d-block character
- D. have zero ionization enthalpy
Explanation: Hydrogen can complete its duplet by gaining one electron.
Isotopes
53. The isotope of hydrogen containing one proton and one neutron is:
- A. deuterium (Correct)
- B. protium
- C. tritium
- D. positronium
Explanation: Deuterium is $^2$H or D.
Isotopes
54. The radioactive isotope of hydrogen is:
- A. tritium (Correct)
- B. protium
- C. deuterium
- D. hydride
Explanation: Tritium is $^3$H and radioactive.
Preparation
55. Hydrogen is commonly prepared in the lab by action of dilute acid on:
- A. zinc (Correct)
- B. copper
- C. silver
- D. gold
Explanation: Zinc reacts readily with dilute acids to liberate H$_2$.
Occurrence
56. In the universe, hydrogen is the:
- A. most abundant element (Correct)
- B. least reactive metal
- C. heaviest non-metal
- D. rarest gas
Explanation: Hydrogen dominates stellar matter.
Molecular form
57. Hydrogen exists as:
- A. H$_2$ molecule (Correct)
- B. H atom only
- C. H$_3$ cluster
- D. monatomic gas
Explanation: Hydrogen is diatomic under normal conditions.
Hydrides
58. Ionic hydrides are generally formed by:
- A. alkali and alkaline earth metals (Correct)
- B. halogens only
- C. transition metals only
- D. noble gases
Explanation: Highly electropositive metals form saline hydrides.
Hydrides
59. Covalent hydrides are commonly formed by:
- A. p-block elements (Correct)
- B. alkali metals only
- C. lanthanoids only
- D. actinoids only
Explanation: Many p-block elements form molecular hydrides.
Hydrides
60. The hydride containing H as H$^-$ is called:
- A. ionic hydride (Correct)
- B. metallic hydride
- C. interstitial hydride
- D. protic solvent
Explanation: Hydrogen exists as hydride ion in saline hydrides.
Water
61. Heavy water is:
- A. D$_2$O (Correct)
- B. H$_2$O$_2$
- C. T$_2$O
- D. HD
Explanation: Heavy water contains deuterium instead of protium.
Water
62. Hardness of water due to bicarbonates is called:
- A. temporary hardness (Correct)
- B. permanent hardness
- C. saline hardness
- D. metallic hardness
Explanation: Bicarbonate hardness can be removed by boiling.
Water
63. Permanent hardness of water is mainly due to:
- A. chlorides and sulfates of Ca and Mg (Correct)
- B. bicarbonates only
- C. sodium salts only
- D. dissolved oxygen
Explanation: These salts do not decompose on boiling.
Peroxide
64. Hydrogen peroxide has molecular formula:
- A. H$_2$O$_2$ (Correct)
- B. HO$_2$
- C. H$_2$O
- D. H$_2$
Explanation: Hydrogen peroxide contains a peroxide linkage.
Peroxide
65. Oxidation state of oxygen in H$_2$O$_2$ is:
- A. -1 (Correct)
- B. -2
- C. 0
- D. +1
Explanation: Peroxides contain oxygen in -1 state.
Peroxide use
66. Hydrogen peroxide acts as a bleaching agent because it is a:
- A. strong oxidising agent (Correct)
- B. strong reducing agent only
- C. neutral salt
- D. metallic catalyst
Explanation: It releases nascent oxygen in many reactions.
Reducing nature
67. Hydrogen peroxide can act as a reducing agent toward:
- A. strong oxidising agents like KMnO$_4$ (Correct)
- B. alkali metals
- C. noble gases
- D. water
Explanation: H$_2$O$_2$ shows dual redox behavior.
Structure
68. The O-O bond present in hydrogen peroxide is a:
- A. single bond (Correct)
- B. double bond
- C. triple bond
- D. coordinate bond
Explanation: Peroxide has a single O-O linkage.
Water properties
69. Ice floats on water because ice has:
- A. lower density than liquid water (Correct)
- B. higher molecular mass
- C. ionic bonding
- D. greater conductivity
Explanation: Open hydrogen-bonded structure lowers density.
Hydrogen bond
70. High boiling point of water is due to:
- A. extensive hydrogen bonding (Correct)
- B. high atomic mass of hydrogen
- C. metallic bonding
- D. large number of neutrons
Explanation: Intermolecular H-bonding is strong in water.
Dual nature
71. Hydrogen is unique because it resembles both:
- A. alkali metals and halogens (Correct)
- B. noble gases and lanthanoids
- C. alkaline earth metals and actinoids
- D. transition metals and metalloids
Explanation: Its single electron and ability to gain one electron create this duality.
Hydrides
72. Electron-deficient hydrides such as diborane are called:
- A. electron-deficient covalent hydrides (Correct)
- B. saline hydrides
- C. interstitial hydrides
- D. stoichiometric salts
Explanation: They have multicenter bonding and too few electrons for classical structures.
Water treatment
73. Temporary hardness of water can be removed by:
- A. boiling (Correct)
- B. adding NaCl
- C. cooling only
- D. distillation with acid
Explanation: Bicarbonates decompose on heating.
Water treatment
74. Calgon method removes hardness using:
- A. sodium hexametaphosphate (Correct)
- B. alum
- C. bleaching powder
- D. hydrogen peroxide
Explanation: Calgon complexes Ca$^{2+}$ and Mg$^{2+}$ ions.
Hydrogen logic
75. A safe scoring route in this chapter is to separate questions into isotopes, hydrides, water chemistry, and:
- A. hydrogen peroxide behavior (Correct)
- B. electrode potential
- C. unit-cell defects
- D. radioactivity series
Explanation: That split covers most NEET asks cleanly.
Position
76. Hydrogen is placed with alkali metals mainly because it has:
- A. one valence electron (Correct)
- B. high density
- C. metallic lattice
- D. two valence electrons
Explanation: Its configuration is 1s$^1$.
Position
77. Hydrogen also resembles halogens because it can:
- A. gain one electron to form H$^-$ (Correct)
- B. form only cations
- C. show d-block character
- D. have zero ionization enthalpy
Explanation: Hydrogen can complete its duplet by gaining one electron.
Isotopes
78. The isotope of hydrogen containing one proton and one neutron is:
- A. deuterium (Correct)
- B. protium
- C. tritium
- D. positronium
Explanation: Deuterium is $^2$H or D.
Isotopes
79. The radioactive isotope of hydrogen is:
- A. tritium (Correct)
- B. protium
- C. deuterium
- D. hydride
Explanation: Tritium is $^3$H and radioactive.
Preparation
80. Hydrogen is commonly prepared in the lab by action of dilute acid on:
- A. zinc (Correct)
- B. copper
- C. silver
- D. gold
Explanation: Zinc reacts readily with dilute acids to liberate H$_2$.
Occurrence
81. In the universe, hydrogen is the:
- A. most abundant element (Correct)
- B. least reactive metal
- C. heaviest non-metal
- D. rarest gas
Explanation: Hydrogen dominates stellar matter.
Molecular form
82. Hydrogen exists as:
- A. H$_2$ molecule (Correct)
- B. H atom only
- C. H$_3$ cluster
- D. monatomic gas
Explanation: Hydrogen is diatomic under normal conditions.
Hydrides
83. Ionic hydrides are generally formed by:
- A. alkali and alkaline earth metals (Correct)
- B. halogens only
- C. transition metals only
- D. noble gases
Explanation: Highly electropositive metals form saline hydrides.
Hydrides
84. Covalent hydrides are commonly formed by:
- A. p-block elements (Correct)
- B. alkali metals only
- C. lanthanoids only
- D. actinoids only
Explanation: Many p-block elements form molecular hydrides.
Hydrides
85. The hydride containing H as H$^-$ is called:
- A. ionic hydride (Correct)
- B. metallic hydride
- C. interstitial hydride
- D. protic solvent
Explanation: Hydrogen exists as hydride ion in saline hydrides.
Water
86. Heavy water is:
- A. D$_2$O (Correct)
- B. H$_2$O$_2$
- C. T$_2$O
- D. HD
Explanation: Heavy water contains deuterium instead of protium.
Water
87. Hardness of water due to bicarbonates is called:
- A. temporary hardness (Correct)
- B. permanent hardness
- C. saline hardness
- D. metallic hardness
Explanation: Bicarbonate hardness can be removed by boiling.
Water
88. Permanent hardness of water is mainly due to:
- A. chlorides and sulfates of Ca and Mg (Correct)
- B. bicarbonates only
- C. sodium salts only
- D. dissolved oxygen
Explanation: These salts do not decompose on boiling.
Peroxide
89. Hydrogen peroxide has molecular formula:
- A. H$_2$O$_2$ (Correct)
- B. HO$_2$
- C. H$_2$O
- D. H$_2$
Explanation: Hydrogen peroxide contains a peroxide linkage.
Peroxide
90. Oxidation state of oxygen in H$_2$O$_2$ is:
- A. -1 (Correct)
- B. -2
- C. 0
- D. +1
Explanation: Peroxides contain oxygen in -1 state.
Peroxide use
91. Hydrogen peroxide acts as a bleaching agent because it is a:
- A. strong oxidising agent (Correct)
- B. strong reducing agent only
- C. neutral salt
- D. metallic catalyst
Explanation: It releases nascent oxygen in many reactions.
Reducing nature
92. Hydrogen peroxide can act as a reducing agent toward:
- A. strong oxidising agents like KMnO$_4$ (Correct)
- B. alkali metals
- C. noble gases
- D. water
Explanation: H$_2$O$_2$ shows dual redox behavior.
Structure
93. The O-O bond present in hydrogen peroxide is a:
- A. single bond (Correct)
- B. double bond
- C. triple bond
- D. coordinate bond
Explanation: Peroxide has a single O-O linkage.
Water properties
94. Ice floats on water because ice has:
- A. lower density than liquid water (Correct)
- B. higher molecular mass
- C. ionic bonding
- D. greater conductivity
Explanation: Open hydrogen-bonded structure lowers density.
Hydrogen bond
95. High boiling point of water is due to:
- A. extensive hydrogen bonding (Correct)
- B. high atomic mass of hydrogen
- C. metallic bonding
- D. large number of neutrons
Explanation: Intermolecular H-bonding is strong in water.
Dual nature
96. Hydrogen is unique because it resembles both:
- A. alkali metals and halogens (Correct)
- B. noble gases and lanthanoids
- C. alkaline earth metals and actinoids
- D. transition metals and metalloids
Explanation: Its single electron and ability to gain one electron create this duality.
Hydrides
97. Electron-deficient hydrides such as diborane are called:
- A. electron-deficient covalent hydrides (Correct)
- B. saline hydrides
- C. interstitial hydrides
- D. stoichiometric salts
Explanation: They have multicenter bonding and too few electrons for classical structures.
Water treatment
98. Temporary hardness of water can be removed by:
- A. boiling (Correct)
- B. adding NaCl
- C. cooling only
- D. distillation with acid
Explanation: Bicarbonates decompose on heating.
Water treatment
99. Calgon method removes hardness using:
- A. sodium hexametaphosphate (Correct)
- B. alum
- C. bleaching powder
- D. hydrogen peroxide
Explanation: Calgon complexes Ca$^{2+}$ and Mg$^{2+}$ ions.
Hydrogen logic
100. A safe scoring route in this chapter is to separate questions into isotopes, hydrides, water chemistry, and:
- A. hydrogen peroxide behavior (Correct)
- B. electrode potential
- C. unit-cell defects
- D. radioactivity series
Explanation: That split covers most NEET asks cleanly.
Position
101. Hydrogen is placed with alkali metals mainly because it has:
- A. one valence electron (Correct)
- B. high density
- C. metallic lattice
- D. two valence electrons
Explanation: Its configuration is 1s$^1$.
Position
102. Hydrogen also resembles halogens because it can:
- A. gain one electron to form H$^-$ (Correct)
- B. form only cations
- C. show d-block character
- D. have zero ionization enthalpy
Explanation: Hydrogen can complete its duplet by gaining one electron.
Isotopes
103. The isotope of hydrogen containing one proton and one neutron is:
- A. deuterium (Correct)
- B. protium
- C. tritium
- D. positronium
Explanation: Deuterium is $^2$H or D.
Isotopes
104. The radioactive isotope of hydrogen is:
- A. tritium (Correct)
- B. protium
- C. deuterium
- D. hydride
Explanation: Tritium is $^3$H and radioactive.
Preparation
105. Hydrogen is commonly prepared in the lab by action of dilute acid on:
- A. zinc (Correct)
- B. copper
- C. silver
- D. gold
Explanation: Zinc reacts readily with dilute acids to liberate H$_2$.
Occurrence
106. In the universe, hydrogen is the:
- A. most abundant element (Correct)
- B. least reactive metal
- C. heaviest non-metal
- D. rarest gas
Explanation: Hydrogen dominates stellar matter.
Molecular form
107. Hydrogen exists as:
- A. H$_2$ molecule (Correct)
- B. H atom only
- C. H$_3$ cluster
- D. monatomic gas
Explanation: Hydrogen is diatomic under normal conditions.
Hydrides
108. Ionic hydrides are generally formed by:
- A. alkali and alkaline earth metals (Correct)
- B. halogens only
- C. transition metals only
- D. noble gases
Explanation: Highly electropositive metals form saline hydrides.
Hydrides
109. Covalent hydrides are commonly formed by:
- A. p-block elements (Correct)
- B. alkali metals only
- C. lanthanoids only
- D. actinoids only
Explanation: Many p-block elements form molecular hydrides.
Hydrides
110. The hydride containing H as H$^-$ is called:
- A. ionic hydride (Correct)
- B. metallic hydride
- C. interstitial hydride
- D. protic solvent
Explanation: Hydrogen exists as hydride ion in saline hydrides.
Water
111. Heavy water is:
- A. D$_2$O (Correct)
- B. H$_2$O$_2$
- C. T$_2$O
- D. HD
Explanation: Heavy water contains deuterium instead of protium.
Water
112. Hardness of water due to bicarbonates is called:
- A. temporary hardness (Correct)
- B. permanent hardness
- C. saline hardness
- D. metallic hardness
Explanation: Bicarbonate hardness can be removed by boiling.
Water
113. Permanent hardness of water is mainly due to:
- A. chlorides and sulfates of Ca and Mg (Correct)
- B. bicarbonates only
- C. sodium salts only
- D. dissolved oxygen
Explanation: These salts do not decompose on boiling.
Peroxide
114. Hydrogen peroxide has molecular formula:
- A. H$_2$O$_2$ (Correct)
- B. HO$_2$
- C. H$_2$O
- D. H$_2$
Explanation: Hydrogen peroxide contains a peroxide linkage.
Peroxide
115. Oxidation state of oxygen in H$_2$O$_2$ is:
- A. -1 (Correct)
- B. -2
- C. 0
- D. +1
Explanation: Peroxides contain oxygen in -1 state.
Peroxide use
116. Hydrogen peroxide acts as a bleaching agent because it is a:
- A. strong oxidising agent (Correct)
- B. strong reducing agent only
- C. neutral salt
- D. metallic catalyst
Explanation: It releases nascent oxygen in many reactions.
Reducing nature
117. Hydrogen peroxide can act as a reducing agent toward:
- A. strong oxidising agents like KMnO$_4$ (Correct)
- B. alkali metals
- C. noble gases
- D. water
Explanation: H$_2$O$_2$ shows dual redox behavior.
Structure
118. The O-O bond present in hydrogen peroxide is a:
- A. single bond (Correct)
- B. double bond
- C. triple bond
- D. coordinate bond
Explanation: Peroxide has a single O-O linkage.
Water properties
119. Ice floats on water because ice has:
- A. lower density than liquid water (Correct)
- B. higher molecular mass
- C. ionic bonding
- D. greater conductivity
Explanation: Open hydrogen-bonded structure lowers density.
Hydrogen bond
120. High boiling point of water is due to:
- A. extensive hydrogen bonding (Correct)
- B. high atomic mass of hydrogen
- C. metallic bonding
- D. large number of neutrons
Explanation: Intermolecular H-bonding is strong in water.
Dual nature
121. Hydrogen is unique because it resembles both:
- A. alkali metals and halogens (Correct)
- B. noble gases and lanthanoids
- C. alkaline earth metals and actinoids
- D. transition metals and metalloids
Explanation: Its single electron and ability to gain one electron create this duality.
Hydrides
122. Electron-deficient hydrides such as diborane are called:
- A. electron-deficient covalent hydrides (Correct)
- B. saline hydrides
- C. interstitial hydrides
- D. stoichiometric salts
Explanation: They have multicenter bonding and too few electrons for classical structures.
Water treatment
123. Temporary hardness of water can be removed by:
- A. boiling (Correct)
- B. adding NaCl
- C. cooling only
- D. distillation with acid
Explanation: Bicarbonates decompose on heating.
Water treatment
124. Calgon method removes hardness using:
- A. sodium hexametaphosphate (Correct)
- B. alum
- C. bleaching powder
- D. hydrogen peroxide
Explanation: Calgon complexes Ca$^{2+}$ and Mg$^{2+}$ ions.
Hydrogen logic
125. A safe scoring route in this chapter is to separate questions into isotopes, hydrides, water chemistry, and:
- A. hydrogen peroxide behavior (Correct)
- B. electrode potential
- C. unit-cell defects
- D. radioactivity series
Explanation: That split covers most NEET asks cleanly.

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