Q41. The reaction between zinc and sulfuric acid to produce hydrogen gas is an example of:
A) Neutralization
B) Redox reaction
C) Displacement reaction
D) Precipitation reaction
Answer: C) Displacement reaction
Explanation: In the reaction, zinc displaces hydrogen from sulfuric acid, producing hydrogen gas and zinc sulfate, making it a displacement reaction.
Q42. Which of the following hydrides is not a covalent hydride?
A) NH₃
B) H₂O
C) NaH
D) CH₄
Answer: C) NaH
Explanation: Sodium hydride (NaH) is an ionic hydride, not a covalent hydride. The others form covalent bonds with hydrogen.
Q43. The preparation of hydrogen by electrolysis involves the following half-reaction at the cathode:
A) 2H⁺ + 2e⁻ → H₂
B) O₂ + 4e⁻ → 2O²⁻
C) H₂O → 2H⁺ + ½O₂ + 2e⁻
D) 2OH⁻ → H₂O + ½O₂ + 2e⁻
Answer: A) 2H⁺ + 2e⁻ → H₂
Explanation: During electrolysis, at the cathode, hydrogen ions (H⁺) are reduced to form hydrogen gas.
Q44. Which of the following is true regarding hydrogen’s position in the periodic table?
A) It is placed only in Group 1.
B) It is placed only in Group 17.
C) It shows properties similar to both alkali metals and halogens.
D) It is placed at the center of the periodic table.
Answer: C) It shows properties similar to both alkali metals and halogens.
Explanation: Hydrogen shows similarity to alkali metals by losing an electron to form H⁺ and to halogens by gaining an electron to form H⁻.
Q45. Which of the following is an example of an interstitial hydride?
A) NaH
B) H₂O
C) TiHₓ
D) CH₄
Answer: C) TiHₓ
Explanation: Interstitial hydrides are formed when hydrogen occupies the interstices (voids) of metal lattices. Titanium hydride (TiHₓ) is an example.
Q46. The following gas is often used to detect leaks in pipelines because of its low molecular weight and high diffusion rate:
A) Oxygen
B) Helium
C) Hydrogen
D) Nitrogen
Answer: C) Hydrogen
Explanation: Hydrogen is used in detecting leaks due to its low molecular weight, which allows it to diffuse quickly through small gaps.
Q47. Which of the following compounds is an electron-deficient hydride?
A) B₂H₆
B) H₂S
C) NH₃
D) H₂O
Answer: A) B₂H₆
Explanation: Diborane (B₂H₆) is an electron-deficient compound because boron does not have enough electrons to form conventional two-electron bonds with hydrogen.
Q48. Which of the following is not a property of heavy water (D₂O)?
A) It has a higher boiling point than ordinary water.
B) It is used as a moderator in nuclear reactors.
C) It reacts more slowly than ordinary water.
D) It can be used as drinking water.
Answer: D) It can be used as drinking water.
Explanation: Heavy water is toxic if consumed in large quantities, and it is not suitable for drinking.
Q49. The dihydrogen molecule (H₂) has:
A) Ionic bonding
B) Polar covalent bonding
C) Non-polar covalent bonding
D) Metallic bonding
Answer: C) Non-polar covalent bonding
Explanation: The H₂ molecule has non-polar covalent bonding because both hydrogen atoms share electrons equally.
Q50. The oxidation state of hydrogen in hydrides of alkali metals is:
A) +1
B) -1
C) 0
D) +2
Answer: B) -1
Explanation: In metal hydrides like sodium hydride (NaH), hydrogen has an oxidation state of -1, as it gains an electron from the metal.
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