The correct options are
A Formation of delta
B Cottrel precipitator
Through its course, a river carries charged colloidal particles like clay, sand and other materials. What happens when a colloidal solution is treated with high concentrations of electrolytes?
Before we go into that, why does a colloidal solution remain stable? The dispersed phase particles are charged and they neither aggregate together nor do they settle down because of gravity.
Sea water is a huge store house of many types electrolytes dissolved in it. As soon as river water comes in contact with sea water, the charged ions in the sea water get adsorbed on the surface of the dispersed phase and coagulate the suspended colloidal particles. Thus the level of the river bed rises and forces the river to adopt an alternate course and a delta is formed eventually.
Smoke is colloidal system in which solids like dust and particles of carbon are dispersed in air. These particles carry charges and when they are made to pass through a chamber containing electrodes connected to high potential, these charged particles get discharged and precipitate. Thus, harmful particulate matter are eliminated. This process is carried out in a Cottrel precipitator.