Question

Some kinds of jewellery are cleaned by soap, water and a drop of ammonia. Which of the following should not be cleaned in this way?
A. rolled-gold plate jewellery
B. gold-filled jewellery
C. silver-filled jewellery
D. gold-electroplated jewellery

Answer 1

To answer this question we should know what is a rolled-gold plate, gold-filled, silver-filled, and gold-electroplated jewellery and how soap affects the jewellery. Gold is a reactive metal. The soap contains the basic compounds which cause the removal of gold plates from the surface of jewellery.

Complete step by step answer:
When another metal such copper. Silver or brass is placed in between the sheets of gold and the sheets are heated so the metal mixes well into each other. This gold is known as rolled gold. Jewellery of rolled-gold looks like real gold jewellery.
Gold-filled jewellery is the jewellery containing gold is filled with pressure from other metal sheets.
Silver-filled jewellery, silver is filled with pressure in other metal sheets.
Gold-electroplated jewellery contains a thin layer of gold at the outer surface of jewellery. The jewellery is made up of other metal. Only the outermost layer contains gold. The jewellery is covered with a thin layer of gold by using an electroplating technique. The gold layer does not have bonding with another metal of the jewellery, so it fed off on reacting with soap. Thus gold plated jewellery should not be treated with soap.So, gold-electroplated jewellery should not be cleaned by soap, water and a drop of ammonia.
Therefore, option (D) gold-electroplated jewellery, is correct.
Note: All types including rolled-gold, Gold-filled, or silver-filled the main content of the jewellery is gold. The presence of another metal decreases the reactivity of gold. In electroplated jewellery the main metal of the jewellery is not gold. Only the outer surface contains a pure gold layer as it is of pure gold so it is reactive. Electroplating technique is used for the protection of one metal by covering it with another metal. By applying the direct current, the metal gets electrons and gets reduced at the cathode forming the layer which deposited at the electrode.