Rusting of iron requires which two chemicals in contact with the metal?
A{'text': 'Oxygen and hydrogen only', 'label': 'A'}
B{'text': 'Chlorine and nitrogen', 'label': 'B'}
C{'text': 'Water and oxygen', 'label': 'C'}
D{'text': 'Only nitrogen from air', 'label': 'D'}
Answer & Solution
Correct answer: C. {'text': 'Water and oxygen', 'label': 'C'}
1. Corrosion is an electrochemical process.
2. Rusting occurs when iron is exposed to moisture (H₂O) and oxygen (O₂).
3. Iron acts as anode: Fe → Fe²⁺ + 2e⁻.
4. Oxygen at cathode: O₂ + 4H⁺ + 4e⁻ → 2H₂O; overall product is hydrated Fe₂O₃ (rust).
_Source: NCERT Class 12 Chemistry, Unit 3 "Electrochemistry", §3.8_
Related questions
For an electrochemical cell operating spontaneously, ΔG° is related to E°_cell byWhich of the following statements about electrode potentials is INCORRECT?The overall cell reaction of the lead storage battery on discharge isThe primary cell that cannot be reused after its EMF drops to zero is exemplified byFuel cells directly convertThe specific conductivity of a 0.1 M KCl solution is 1.29 × 10⁻² S/cm. The molar conductivMolar conductivity of a strong electrolyte at concentration c is related to its limiting vFor a Cu-Zn Daniell cell, the emf is measured to be 1.10 V under standard conditions. If [