Study the given flow chart carefully.
 

Changes i, ii, iii and iv could be respectively.

Based on the properties of materials or things they have been classified into different categories. 
Forest fires and Earthquakes $\to$ Undesirable change 
Low and high tides, opening of a morning glory flower $\to$Periodic change
Sublimation of camphor and Blowing of balloon $\to$ Reversible change
Bursting of crackers and Breaking of glass $\to$ Fast change