Give a short answer to the question given below.
 
1. What is rust?
 When iron is exposed to moist air, it forms a layer of  on its surface. This compound is known as rust.
 
2. Give the equation for the formation of rust.
 The  equation for the formation of rust is
 
3. Which of the following is necessary for rusting of iron?
The necessary conditions required for rusting are the
 
4. What is electroplating?
Electroplating is a method of