The average thickness of ozone layer in stratosphere is about _______________ dobson unit (DU)?

There are thirteen metals which are treated as pollutants. Which of the following metals is not a pollutant ?

A. Mercury

B. Arsenic

C. Aluminium

D. Lead

On prolonged exposure to high concentration of carbon monoxide (> 5000 ppm), man dies because __________________?

A. Of clotting of blood

B. Of jamming of respiratory tract

C. It forms carboxyhemoglobin by combining with haemoglobin of blood, thereby making it incapable of absorbing oxygen

D. It forms CO2 by combining with oxygen present in the blood

In water treatment plant, zeolite process is used to remove the _____________ of water?

A. Acidity

B. Alkalinity

C. Hardness

D. Iron & zinc

Disinfection of water is done to remove ______________________?

A. Color

B. Bad taste

C. Foul odour

D. Bacteria

Noise level audible to audience sitting in the 5th row from the stage during a large orchestra show corresponds to about _______________ decibels?

A. 105

B. 135

C. 160

D. 185