Question

Smoke precipitator works on the principle of:
A) Distribution law
B) Neutralization of charge on colloids
C) Le-Chatelier’s principle
D) Addition of electrolytes

Answer 1

Hint: We know that smoke is a collection of very tiny particles of unburned carbon, tiny droplets of tar and many other chemicals. When smoke is formed, the tiny solid particles get dispersed in air. Thus, smoke is an aerosol in which the dispersion phase is solid and the dispersion medium is a gas.

 Complete answer:We know that smoke contains tiny particles of unburned carbon. Smoke is a colloidal solution of solid particles like carbon, dust which are dispersed in air.
Smoke is a main source of air pollution. The particles of smoke are injurious to health. Thus, the particles of smoke need to be precipitated.
Smoke precipitator is a device that removes smoke or other particles from air by using high voltage electrostatics.
The smoke precipitator forces dirty flue gas between two electrodes. One electrode has a high negative charge and when the particles of the smoke move past the negatively charged electrode the particles become negatively charged.
The other electrode is positively charged. The negatively charged particles get attracted to the positively charged electrode and stick there.
The particles of carbon are charged particles and they cannot be precipitated. Thus, the precipitation of smoke particles is done by the smoke precipitator which neutralizes the charges on the particles of the smoke.
Thus, smoke precipitator works on the principle of neutralization of charge on colloids.

Thus, the correct option is (B).

Note: Smoke is carried away and the particles of smoke drop. Thus, smoke is grey in colour. The smoke precipitator collects the particles of carbon and only pure air is left behind. The positively charged electrode of the smoke precipitator needs to be cleaned very often for clearing the collected soot.