Assertion (A): Aluminum is highly reactive but is used for making cooking utensils. Reason (R): Aluminum forms a protective layer of aluminum oxide on its surface. MCQ with Answer and Explanation
Assertion (A): Aluminum is highly reactive but is used for making cooking utensils. Reason (R): Aluminum forms a protective layer of aluminum oxide on its surface.
A. A is true but R is false.
B. Both A and R are true but R is NOT the correct explanation of A.
C. A is false but R is true.
D. Both A and R are true and R is the correct explanation of A.
Answer: Option D
Solution (By JKExamLibrary)
Aluminum is a highly reactive metal, yet it is widely used for cookware. This is because it rapidly reacts with atmospheric oxygen to form a thin, tough, and invisible layer of aluminum oxide (Al2O3) on its surface. This passivation layer prevents further corrosion and reaction with food.
Explanation:
NH₃ has a lone pair on nitrogen; it donates this pair to H⁺ to form a coordinate (dative) bond, where both electrons in the bond come from nitrogen. The resulting NH₄⁺ has four equivalent N-H bonds.
Explanation:
High-concentration H₂O₂ (e.g., 80-90%) decomposes rapidly in the presence of a catalyst to produce superheated steam and oxygen: 2H₂O₂ → 2H₂O + O₂ + heat. This generates high-pressure gas used for propulsion (monopropellant) or as oxidizer in bipropellant systems. It is not a fuel; it provides oxygen for combustion. It must be handled carefully due to instability.
Explanation:
Aqua regia (royal water) is a 3:1 mixture of concentrated HCl and HNO₃. It can dissolve noble metals gold and platinum by forming complex ions. Freshly prepared, it is a fuming yellow liquid. Used in etching and cleaning.
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