Question

When items of jewellery made of base metals like copper, iron or nickel are placed in a solution containing a compound of gold, a film of gold is deposited by:
A.cooling to 5 degree centigrade
B.adding acid
C.heating
D.passing an electric current

Answer 1

Hint: The process that creates a metal coating on a solid substrate through the reduction of cations of that metal by the means of passing direct electric current.

Complete step by step answer:
Electroplating is the process in which a layer of a metal is deposited on metallic or non-metallic electrodes by the electrolysis in an electrolytic cell. The main idea is to use electricity to coat a relatively dull metal, such as copper, with a very thin layer of another, more precious metal, such as gold or silver. Besides making cheap metals look expensive, electroplating has lots of other uses. It is used to make things rust-resistant. Some examples of this are: to produce a variety of useful alloys like brass and bronze, and even, it can make plastic look like metal. Electroplating changes the physical, chemical, and mechanical properties of any work piece.
There are different types of electroplating such as mass plating which is also known as barrel plating, rack plating, continuous plating and in line plating.
When items of jewellery made of base metals like copper (Cu), Iron (Fe), or Nickel (Ni) are placed in a solution containing a compound of gold, a film of gold is deposited by the process of electroplating, in which passing of an electric current is needed.

Therefore, the correct answer is option (D).

Note: The coating that is applied by electroplating is often around 0.0002 inches thick. By creating a chemical bond, the plating is almost a permanent addition to the surface of the base metal. This means that it will not just naturally fall off. But however, plating can be worn off over months and years of use and wear.