Which of the following is an example of a negative catalyst? MCQ with Answer and Explanation

Which of the following is an example of a negative catalyst?
A. Alcohol in chloroform storage to prevent phosgene formation
B. Fe in Haber process
C. Pt in SO₂ oxidation
D. MnO₂ in H₂O₂ decomposition
Answer: Option A
Solution (By JKSSB Mock Tests)
A small amount of ethanol (alcohol) is added to chloroform to inhibit its oxidation by air to toxic phosgene (COCl₂) and HCl. Ethanol acts as a negative catalyst (stabilizer) by consuming any formed phosgene. MnO₂, Pt, Fe are positive catalysts. Negative catalysts are also called inhibitors, used to prevent undesirable reactions.

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Which of the following is used to remove grease stains from clothes?
A. Ethanol
B. Detergent
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Correct Answer: Option B


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A. Nitrogen dioxide and copper nitrate
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Correct Answer: Option A


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Cu + 4HNO₃ (conc.) → Cu(NO₃)₂ + 2NO₂ + 2H₂O. Dilute HNO₃ gives NO instead of NO₂. Copper does not produce H₂ with HNO₃ because HNO₃ is an oxidizing acid.

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Question #3
Which of the following is NOT a characteristic of an ideal gas?
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C. No intermolecular forces
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Correct Answer: Option D


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