Q91. Which of the following compounds does not exist?
A) NCl₃
B) PCl₅
C) BiCl₅
D) PF₅
Answer: C) BiCl₅
Explanation: Bismuth (Bi) does not form BiCl₅ due to the inert pair effect. It commonly exhibits a +3 oxidation state, so BiCl₃ exists, but BiCl₅ does not.
Q92. Which of the following is a non-metallic oxide?
A) B₂O₃
B) PbO
C) CO
D) SnO₂
Answer: A) B₂O₃
Explanation: Boron trioxide (B₂O₃) is a non-metallic oxide of boron. Lead oxide (PbO), carbon monoxide (CO), and tin dioxide (SnO₂) are metallic or semi-metallic oxides.
Q93. Which of the following oxides of nitrogen is commonly known as “laughing gas”?
A) NO₂
B) N₂O
C) NO
D) N₂O₅
Answer: B) N₂O
Explanation: Nitrous oxide (N₂O) is commonly known as laughing gas due to its euphoric effects when inhaled. It is used as an anesthetic and analgesic in medicine.
Q94. Which of the following statements is correct for boron?
A) It forms only covalent compounds.
B) It forms ionic as well as covalent compounds.
C) It exists as a liquid at room temperature.
D) It is a poor conductor of electricity.
Answer: A) It forms only covalent compounds.
Explanation: Boron, being a small non-metal, forms only covalent compounds, unlike other elements in its group that can form both ionic and covalent compounds.
Q95. The process by which nitrogen is fixed into ammonia in the Haber process involves:
A) High temperature and pressure
B) Low temperature and high pressure
C) Low temperature and pressure
D) Moderate temperature and high pressure
Answer: A) High temperature and pressure
Explanation: In the Haber process, nitrogen and hydrogen gases are reacted at high temperature (400-500°C) and high pressure (200-300 atm) with an iron catalyst to form ammonia (NH₃).
Q96. Which of the following compounds is used in matches?
A) Red phosphorus
B) White phosphorus
C) Phosphine
D) Phosphorus pentoxide
Answer: A) Red phosphorus
Explanation: Red phosphorus is used on the striking surfaces of matchboxes due to its stability and relatively safe reaction with the oxidizing agents present in match heads.
Q97. What is the major product formed when aluminium reacts with chlorine?
A) AlCl₂
B) AlCl₃
C) Al₂Cl₅
D) AlCl
Answer: B) AlCl₃
Explanation: Aluminium reacts with chlorine to form aluminium chloride (AlCl₃) in a 1:3 stoichiometric ratio. AlCl₃ is an important compound used in various chemical processes.
Q98. The hydrolysis of PCl₅ in water leads to the formation of:
A) HCl and POCl₃
B) HCl and H₃PO₄
C) HCl and PCl₃
D) HCl and H₃PO₂
Answer: B) HCl and H₃PO₄
Explanation: The hydrolysis of phosphorus pentachloride (PCl₅) with water produces hydrochloric acid (HCl) and phosphoric acid (H₃PO₄).
Q99. Which of the following forms the strongest hydrogen bonds?
A) Ammonia
B) Phosphine
C) Arsenic hydride
D) Antimony hydride
Answer: A) Ammonia
Explanation: Ammonia (NH₃) forms strong hydrogen bonds due to the high electronegativity of nitrogen and the presence of lone pairs of electrons.
Q100. Which of the following hydrides of Group 15 is the least thermally stable?
A) NH₃
B) PH₃
C) AsH₃
D) SbH₃
Answer: D) SbH₃
Explanation: The thermal stability of hydrides decreases down the group. Antimony hydride (SbH₃) is the least stable because of the large atomic size and weak bonding in the Sb-H bond.
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