Question

Which one of the processes does not involve coagulation?
A. Peptization
B. Formation of delta
C. Purification of water using alum
D. Tanning of leather using tannin

Answer 1

Hint: Coagulation of colloidal particles is peptization. A delta is formed due to coagulation of sand and mud. During purification of water an Alum coagulates all the sand impurities.
The process of treating skin and other parts of an animal to obtain usable leather is known as tanning.

Complete step by step answer:
Peptization is the process used for stable dispersion of colloidal particles in dispersion medium. It may be defined as a process of converting a precipitate into colloidal sol by shaking it with a dispersion medium in the presence of a small amount of electrolyte. When colloidal particles bear the same sign electric charge, they mutually repel each other and cannot aggregate together. Colloidal solutions of certain substances like AlCl3 are very difficult to settle. When an electrolyte which is also known as peptizing agent is added to the solution, the charge on ions get neutralised and they coagulate to form big particles and form a colloidal sol.
A delta is a landform that is formed at the junction where a river meets the sea. Formation of a river delta is a slow process. As rivers flow toward their outlets from higher elevations, they carry mud, sand, and gravel particles and deposits at the mouths where rivers and larger bodies of water like sea or ocean meet. Over time these sediment particles build up or coagulate at the mouth, extending into the ocean or lake. As these areas continue to grow the water becomes shallower and eventually, landforms begin to rise above the surface of the water forming delta.
When water contains very fine impurities suspended in it. It makes it unfit for drinking and for other uses.it is very difficult to remove these particles as they do not get settled easily. When a piece of an Alum is suspended in it with the help of a thread all the finer impurities get attracted towards it and coagulate at the surface of alum, which is thrown out later. This process is called Loading. Tanning of lather is a process to remove unwanted hairs, germs etc present on animal skin or other parts by treating it with suitable chemicals and to convert it into suitable form of leather. First it is disinfected then hairs are removed. After that softening is done. In this process no aggregation or coagulation is involved

So, the final answer to this question is option D Tanning of leather using tannin.

Note:
Coagulation means to aggregate, flocculate or to deposit at one place. When smaller particles deposit at one place automatically or by adding some chemicals or under the influence of wind or water current it is coagulation.