NEET Previous Year Questions (2014-2024): Hydrogen (Old NCERT) | Chemistry Class 11 PDF Download

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Q.1. 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 elements.
E. Hydrogen reduces oxides of metals that are more active than iron.
Choose the most appropriate answer from the options given below:
(a) B, C, D, E only
(b) B, D only
(c) D, E only
(d) A, B, C only
Ans: c
Statement A, B, C are correct
(D) H – H bond dissociation energy is maximum as compared to single bond between two atom of any element.  
(E) Hydrogen reduces oxides of metal that are less active than iron.


Q.2. Match List-I with List-II

Choose the correct answer from the options given below:    (2022)
(a) (a) – (i), (b) – (ii), (c) – (iv), (d) – (iii)  
(b) (a) – (ii), (b) – (iii), (c) – (iv), (d) – (i)  
(c) (a) – (iv), (b) – (i), (c) – (ii), (d) – (iii)
(d) (a) – (iii), (b) – (i), (c) – (ii), (d) – (iv)
Ans: c
MgH₂ → Ionic  
GeH₄ → electron precise
B₂H₆ → electron deficient
HF → electron rich

Q.3. Tritium, a radioactive isotope of hydrogen, emits which of the following particles?     (2021)
(a) Gamma (γ)
(b) Neutron (n)
(c) Beta (β)
(d) Alpha (α)
Ans: c

Tritium (₁³H or T) This isotope of hydrogen is radioactive and emits low energy β-particle.
It has one proton and two neutrons in the nucleus. The concentration of tritium is very low.
It is just about one atom per 10¹⁸ atoms of protium.

Q.4. Match the following and identify the correct option.     (2020)


Ans: c
⇒ CO(g) + H₂(g) = Water gas or synthesis gas
⇒ Temporary hardness of water is due to bicarbonates of Ca²⁺ & Mg²⁺
⇒ B₂H₆ is a electron deficient compound due to presence of banana bond.
⇒ H₂O₂ open book like structure which is non-planar

Q.5. The method used to remove temporary hardness of water is :    (2019)
(a) Calgon's method
(b) Clark's method
(c) Ion-exchange method
(d) Synthetic resins method
Ans: b

Clark's method is used to remove temporary hardness of water, in which bicarbonates of calcium and magnesium are reacted with slaked lime Ca(OH)₂.

Q.6. Which of the following statements about hydrogen is incorrect ?    (2016)
(a) Dihydrogen does not act as a reducing agent.
(b) Hydrogen has three isotopes of which tritium is the most common.
(c) Hydrogen never acts as cation in ionic salts.
(d) Hydronium ion, H3O⁺ exists freely in solution.
Ans: a,b
Dihydrogen act as reducing agent for eg: 3H₂ + N₂ → 2NH₃
Hydrogen has three isotopes of which protium (₁H¹) is the most common.

Isotopes of HydrogenQ.7. (A) H₂O₂ +O₃ → H₂O+ 2O₂
(B) H₂O₂ + Ag₂O → 2Ag + H₂O + O₂
Role of hydrogen peroxide in the above reactions is respectively :    (2014)
(a) reducing in (A) and (B)
(b) oxidizing in (A) and (B)
(c) oxidizing in (A) and reducing in (B)
(d) reducing in (A) and oxidizing in (B)
Ans: a
H₂O₂ acts as reducing agent in both the reactions
H₂O₂ +O₃ → H₂O+ 2O₂
H₂O₂ + Ag₂O → 2Ag + H₂O + O₂