Effects of Oxidation in Daily Life (Corrosion, Rancidity) MCQs

Q1. Which of the following prevents rusting by sacrificial protection (NCERT)?

• A.painting the surface
• B.keeping it in dry air
• C.connecting a more reactive metal like zinc or magnesium
• D.greasing the surface

Answer: C. connecting a more reactive metal like zinc or magnesium

Q2. Which is NOT a method to prevent rusting of iron?

• A.Storing iron in moist air
• B.Galvanising with zinc
• C.Applying grease or oil
• D.Painting the surface

Answer: A. Storing iron in moist air

Quick parse - a typical chemistry numerical. We are after the quantity the stem asks for. Tool of choice - hence the answer = Storing iron in moist air. Rearrange it for the unknown before substituting. Common-sense check: corrosion of iron: 4Fe + 3O2 + 2xH2O -> 2Fe2O3.xH2O (hydrated ferric oxide). Lock in option A) Storing iron in moist air. Trap-watch: option B) 'Galvanising with zinc' fails since Zinc gives sacrificial protection; option C) 'Applying grease or oil' is wrong because Oil forms a protective barrier.

Q3. Which everyday practice does NOT slow rancidity?

• A.Frying food repeatedly in the same exposed oil
• B.Vacuum packing
• C.Adding BHA/BHT antioxidants
• D.Refrigerating fried snacks

Answer: A. Frying food repeatedly in the same exposed oil