Question

Smoke precipitator works on the principle of:
A.distribution law
B.neutralization of charge on colloids
C.Le Chaterlier’s principle
D.addition of electrolytes

Answer 1

Hint: To solve the above question first we need to understand the meaning of smoke and then we can understand smoke precipitator. We know that smoke consists of a collection of airborne particles and gases emitted when a particle undergoes the process of combustion or pyrolysis.

Complete step by step answer:
As we know that the smoke coming out of the chimneys contains a lot of unburnt Carbon particles. Also, smoke is the part of a colloidal solution of the solid particles like carbon, arsenic, and some dust particles, etc. We need to remember that these smoke particles are injurious to health. So, these particles need to be precipitated.
The carbon particles are charged particles so they cannot be precipitated. If we place a metal plate of oppositely charged particles then it is used for precipitation. Thus, the precipitation is done by the Cottrell smoke precipitator which neutralizes the charge on the carbon particles and neutralizes them. In this way, smoke coming out of the chimneys gets free from the charged particles. There are different chemicals, including aldehydes, acid gases, sulfur dioxide, nitrogen oxides, polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, styrene, metals and dioxins present in smoke.
Thus, the smoke precipitator works on the principle of neutralization of charge on colloids.

$\therefore$The option B is correct answer.

Note:
 Now, we know that smoke is carried away and the smoke particles drop. So, the smoke turns gray and eventually turns out to be white. When the flames touch a surface the gas is black in color. Also, remember that the hotter the smoke, the blacker it is in color.