Q51. Which method is not suitable for the laboratory preparation of hydrogen?
A) Reaction of zinc with dilute sulfuric acid
B) Electrolysis of water
C) Reaction of aluminum with sodium hydroxide
D) Reaction of calcium with cold water
Answer: D) Reaction of calcium with cold water
Explanation: The reaction of calcium with cold water produces hydrogen, but it is too vigorous and exothermic, making it unsafe for laboratory preparation.
Q52. The oxidation state of hydrogen in hydrogen peroxide (H₂O₂) is:
A) 0
B) -1
C) +1
D) -2
Answer: C) +1
Explanation: In hydrogen peroxide, hydrogen has an oxidation state of +1, while oxygen has an oxidation state of -1.
Q53. Which of the following metal hydrides is ionic in nature?
A) CaH₂
B) NH₃
C) H₂O
D) PH₃
Answer: A) CaH₂
Explanation: Calcium hydride (CaH₂) is an ionic hydride because it consists of Ca²⁺ and H⁻ ions.
Q54. The hydrogen gas evolved in the reaction between zinc and hydrochloric acid is collected by:
A) Upward displacement of air
B) Downward displacement of water
C) Downward displacement of air
D) None of the above
Answer: B) Downward displacement of water
Explanation: Hydrogen is collected by downward displacement of water because it is insoluble in water and lighter than air.
Q55. The reaction of hydrogen with which of the following will produce ammonia?
A) Oxygen
B) Nitrogen
C) Chlorine
D) Sulfur
Answer: B) Nitrogen
Explanation: Hydrogen reacts with nitrogen under specific conditions (Haber process) to form ammonia (NH₃).
Q56. Which statement is true about hydrogen peroxide (H₂O₂)?
A) It is a strong reducing agent only.
B) It is a strong oxidizing agent only.
C) It can act as both an oxidizing and reducing agent.
D) It is always neutral in reactions.
Answer: C) It can act as both an oxidizing and reducing agent.
Explanation: Hydrogen peroxide can act as both an oxidizing and reducing agent, depending on the reactants.
Q57. The presence of deuterium in water molecules makes it:
A) More reactive than ordinary water
B) More stable than ordinary water
C) A weaker solvent than ordinary water
D) Less stable than ordinary water
Answer: B) More stable than ordinary water
Explanation: Heavy water (D₂O) is more stable than ordinary water (H₂O) because the bond between deuterium and oxygen is stronger than the bond between protium and oxygen.
Q58. Which of the following hydrides is the most stable?
A) LiH
B) NaH
C) KH
D) RbH
Answer: A) LiH
Explanation: Lithium hydride (LiH) is the most stable hydride among alkali metal hydrides because the smaller size of Li⁺ leads to stronger ionic bonds with H⁻.
Q59. Which of the following processes is used for the commercial production of hydrogen?
A) Reaction of zinc with sulfuric acid
B) Lane’s process
C) Electrolysis of brine
D) Haber process
Answer: B) Lane’s process
Explanation: Lane’s process is used commercially for the production of hydrogen by reacting steam with iron at high temperatures.
Q60. Which of the following has the highest bond dissociation enthalpy?
A) H₂
B) O₂
C) N₂
D) F₂
Answer: C) N₂
Explanation: Nitrogen (N₂) has the highest bond dissociation enthalpy due to its triple bond. However, H₂ also has a significantly high bond dissociation energy compared to many other diatomic molecules.
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