NEET Hydrogen PYQs & Practice Questions

10 free NEET Chemistry questions on Hydrogen, starting with previous year questions (2023–2023). Tap “Show answer” to check each one. No login needed.

Topics: Position of Hydrogen in Periodic Table · Isotopes of Hydrogen · Preparation of Hydrogen · Properties of Water · Hydrogen Peroxide · Types of Hydrides · Heavy Water · Hydrogen Peroxide Structure and Properties · Hydrogen Economy and Fuel Cells · Reactions of Hydrogen · The Proton (H+ ion) · Ionic Character of Alkali Metal Hydrides

Q1NEET 2023Properties and Uses of Hydrogen
Which of the following statements are NOT correct? A. Hydrogen is used to reduce heavy metal oxides to metals. B. Heavy water is used to study reaction mechanism. C. Hydrogen is used to make saturated fats from oils. D. The H-H bond dissociation enthalpy is lowest as compared to a single bond between two atoms of any element. E. Hydrogen reduces oxides of metals that are more active than iron. Choose the most appropriate answer from the options given below.
- A. B, D only
- B. D, E only
- C. A, B, C only
- D. B, C, D, E only
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Answer: A — B, D only
Statement D is incorrect because the H-H bond has 1s-1s orbital overlap, which actually gives it a relatively high (not lowest) bond dissociation enthalpy. Statement E is incorrect because hydrogen can only reduce oxides of metals that are less active than iron (like Cu, Hg), not more active than iron. Statements A, B, and C are correct descriptions of hydrogen's uses. So D and E are the statements that are NOT correct.
Q2Position of Hydrogen in Periodic Table
Hydrogen is placed in Group 1 of the periodic table because it:
- A. Has a single electron in its outermost shell like alkali metals
- B. Is a metal like alkali metals
- C. Has the same electronegativity as alkali metals
- D. Forms only ionic compounds like alkali metals
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Answer: —
Hydrogen has one electron in its outermost (1s) shell, similar to alkali metals which also have one valence electron. This electronic configuration is the primary reason for its placement in Group 1, although hydrogen differs from alkali metals in many other properties.
Q3Isotopes of Hydrogen
Which isotope of hydrogen is radioactive?
- A. Protium (¹H)
- B. Deuterium (²H)
- C. Tritium (³H)
- D. Both Deuterium and Tritium
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Answer: B — Deuterium (²H)
Tritium (³H or T) is the radioactive isotope of hydrogen with a half-life of about 12.3 years. It contains 1 proton and 2 neutrons. Protium (¹H) and Deuterium (²H) are stable isotopes.
Q4Preparation of Hydrogen
In the industrial preparation of hydrogen by the Bosch process (steam reforming), what is the catalyst used?
- A. Platinum
- B. Iron with chromium oxide as promoter
- C. Nickel
- D. Vanadium pentoxide
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Answer: B — Iron with chromium oxide as promoter
In the Bosch process (steam reforming), methane reacts with steam at about 1270 K in the presence of a nickel catalyst to produce CO and H₂. The reaction is: CH₄ + H₂O → CO + 3H₂. Nickel is the catalyst used in this process.

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Q5Properties of Water
The unusually high boiling point of water compared to H₂S, H₂Se and H₂Te is due to:
- A. Higher molecular mass of water
- B. Extensive hydrogen bonding in water
- C. Water being a polar molecule
- D. Higher van der Waals forces in water
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Answer: A — Higher molecular mass of water
Water has an unusually high boiling point (373 K) compared to H₂S (213 K), H₂Se (232 K), and H₂Te (271 K) due to extensive intermolecular hydrogen bonding. The small size and high electronegativity of oxygen allows strong O–H···O hydrogen bonds, requiring more energy to break them during vaporization.
Q6Hydrogen Peroxide
The concentration of hydrogen peroxide is expressed in terms of 'volume strength'. A '20 volume' H₂O₂ solution means:
- A. 20 mL of O₂ is liberated per mL of H₂O₂ solution at STP
- B. 20 g of H₂O₂ is present per 100 mL of solution
- C. The solution is 20% by mass of H₂O₂
- D. 20 moles of O₂ is produced per litre of solution
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Answer: —
Volume strength of H₂O₂ is defined as the volume of O₂ liberated at STP from 1 mL of the H₂O₂ solution. Thus, '20 volume' H₂O₂ means 1 mL of the solution liberates 20 mL of O₂ at STP. This is based on the reaction: 2H₂O₂ → 2H₂O + O₂.
Q7Types of Hydrides
Which of the following hydrides is correctly classified as an electron-deficient hydride (Lewis acid)?
- A. NH₃
- B. B₂H₆
- C. HCl
- D. H₂O
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Answer: A — NH₃
Diborane (B₂H₆) is an electron-deficient hydride because boron has only 6 electrons in its valence shell (3 from B + 3 from H bonds), making it a Lewis acid. NH₃ and H₂O are electron-rich hydrides (Lewis bases), while HCl is an electron-precise hydride (saline/covalent).
Q8Heavy Water
Which of the following statements about heavy water (D₂O) is INCORRECT?
- A. Heavy water reacts with F₂ to produce DF and ODF
- B. Heavy water has a higher boiling point than ordinary water
- C. Heavy water is used as a moderator in nuclear reactors
- D. Heavy water is obtained by the fractional distillation of ordinary water followed by electrolysis
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Answer: C — Heavy water is used as a moderator in nuclear reactors
Heavy water is primarily obtained by the electrolysis of water repeatedly, as H₂O is electrolyzed preferentially over D₂O, thus enriching D₂O. Simple fractional distillation is not sufficient as D₂O and H₂O have very similar boiling points (374.4 K vs 373 K). The other statements are correct: D₂O reacts with F₂ giving DF and DOF, it has a higher boiling point, and it is used as a nuclear moderator.

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Q9Hydrogen Peroxide Structure and Properties
In the structure of H₂O₂, the dihedral angle (angle between the two O–H bonds when viewed along the O–O axis) is approximately:
- A. 90° in both gaseous and solid states
- B. 111.5° in gaseous state and 90.2° in solid state
- C. 180° (planar structure) in both states
- D. 104.5° in both gaseous and solid states
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Answer: A — 90° in both gaseous and solid states
H₂O₂ has a non-planar, open book structure. The dihedral angle (the angle between the planes containing H–O–O and O–O–H) is 111.5° in the gaseous phase and 90.2° in the solid state. This non-planar arrangement arises due to lone pair repulsions on the oxygen atoms. The O–O–H bond angle is about 96.8°.
Q10Hydrogen Economy and Fuel Cells
In a hydrogen-oxygen fuel cell, which of the following correctly describes the reactions at the electrodes?
- A. Anode: H₂ + 2OH⁻ → 2H₂O + 2e⁻; Cathode: O₂ + 2H₂O + 4e⁻ → 4OH⁻
- B. Anode: O₂ + 2H₂O + 4e⁻ → 4OH⁻; Cathode: H₂ + 2OH⁻ → 2H₂O + 2e⁻
- C. Anode: H₂ → 2H⁺ + 2e⁻; Cathode: O₂ + 4H⁺ + 4e⁻ → 2H₂O
- D. Both A and C are correct depending on electrolyte used
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Answer: C — Anode: H₂ → 2H⁺ + 2e⁻; Cathode: O₂ + 4H⁺ + 4e⁻ → 2H₂O
In a hydrogen-oxygen fuel cell, the electrode reactions depend on the nature of the electrolyte. In alkaline electrolyte: Anode: H₂ + 2OH⁻ → 2H₂O + 2e⁻; Cathode: O₂ + 2H₂O + 4e⁻ → 4OH⁻ (as in option A). In acidic electrolyte: Anode: H₂ → 2H⁺ + 2e⁻; Cathode: O₂ + 4H⁺ + 4e⁻ → 2H₂O (as in option C). Therefore, both A and C are correct depending on the electrolyte used.

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