Q.Mention any two reasons for creation of Ozone hole. What is Electrostatic Precipitator?

The ozone hole is mainly caused by chlorofluorocarbons (CFCs) and other ozone-depleting gases releasing reactive chlorine/bromine that break down ozone. An electrostatic precipitator cleans smokestack gas by electrically charging dust particles and collecting them on charged plates.

Two reasons for creation of the ozone hole:

1. Chlorofluorocarbons (CFCs): Released from refrigerators, air-conditioners, aerosol sprays and foam, CFCs rise to the stratosphere where UV rays break them to release chlorine (Cl) atoms. Each Cl atom acts catalytically, destroying thousands of ozone (O₃) molecules and thinning the ozone layer (worst over Antarctica — the 'ozone hole').
2. Other ozone-depleting substances: gases such as halons, methyl bromide, carbon tetrachloride and oxides of nitrogen (NOₓ) — the last emitted, for instance, by supersonic aircraft and industry — also react with and deplete stratospheric ozone.

Electrostatic Precipitator (ESP):

• A pollution-control device installed in the chimneys of thermal power plants and industries to remove particulate matter (PM) from flue gases (it can remove over 99% of particulates).
• Working: The exhaust gas passes between electrodes. Charged (negative) electrode wires give the dust particles an electric charge; these charged particles are then attracted to and collected on oppositely charged (positive) collecting plates. The cleaned gas escapes, while the accumulated dust falls off and is removed. …