Question

Dipping iron article into a strongly alkaline solution of sodium phosphate

• A. does not affect the article
• B. forms Fe\(_2\)O\(_3\cdot xH_2O\) on the surface
• C. forms iron phosphate film
• D. forms ferric hydroxide

Hint:

Phosphating produces a protective iron phosphate layer that prevents rusting of iron articles.

Answer 1

The Correct Option is C

Step 1: Identify the process.
Dipping iron in alkaline sodium phosphate solution is a method of phosphating.
Step 2: Formation of protective coating.
In this process, iron reacts with phosphate ions to form a thin, insoluble coating of iron phosphate on the surface.
Step 3: Purpose of coating.
This film prevents direct contact of iron with moisture and oxygen, thus reducing corrosion.
Step 4: Conclusion.
Therefore it forms iron phosphate film.
Final Answer:
\[ \boxed{\text{(C) forms iron phosphate film}} \]