Q30 / 120 · VITEEE 2008 · Chemistry

Dipping iron article into a strongly alkaline solution of sodium phosphate

  • A
    does not affect the article
  • B
    forms $\mathrm{Fe}_{2} \mathrm{O}_{3} . \mathrm{xH}_{2} \mathrm{O}$ on the surface
  • Correct answer
    C
    forms iron phosphate film
  • D
    forms ferric hydroxide

Solution

Rusting of iron is generally promoted in an acidic aqueous medium. Alkaline medium prevents availability of $\mathrm{H}^{+}$ions. Sodium phosphate will cause formation of a protective film of iron phosphate on the iron preventing rusting. These solutions are used in car radiators to prevent rusting of iron parts.

Hence, the correct answer is option: 'C'.

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