CBSE Class 12 · 2020 · Redox Reactions and ElectrochemistryVery Short Answer

Out of zinc and tin, whose coating is better to protect iron objects?

Solution

Zinc.
Zinc (

E^{\circ} = - 0.76

V) is more reactive than iron, so even if the coating is scratched, zinc is oxidised in preference to iron (sacrificial protection).
Tin (

E^{\circ} = - 0.14

V) is less reactive than iron: once a tin coating breaks, iron becomes the anode of the local cell and rusts even faster.

CBSE Class 12 Board · 2020 · Subjective