The earth’s atmosphere is an envelope of gases present upto a height of about ______________ kms?

A. 10
B. 200
C. 1000
D. 2000

Color test of water is done with an instrument called__________________?

A. Tintometer
B. Colorimeter
C. Electro-chemical cell
D. Turbidimeter

The maximum CO2 is emitted into the atmosphere by_________________?

A. Combustion
B. Urea
C. Biomass burning
D. Trees

Water filtration rate in a slow sand filter ranges from ____________ litres/m2/hr?

A. 10 to 20
B. 100 to 200
C. 1500 to 2500
D. 4000 to 5000

A masonry structure built below ground level, where biochemical reaction takes place due to anaerobic bacteria is called___________________?

A. Cesspool
B. Lagoon
C. Skimming mill
D. Septic tank

The maximum permissible noise level to which a man working in a chemical plant can be exposed for eight hours per day is about ____________ decibels?

A. 60
B. 90
C. 105
D. 120

Inhalation of silica dust by human being during hand drilling in mica mining, lead & zinc mining, silica refractory manufacture and in foundries causes___________________?

A. Asphyxiation (suffocation)
B. Shortness of breath
C. Tuberculosis
D. All A., B. and C.

Maximum permissible residual chlorine in treated water should be ____________ mg/litre?

A. 0.001 to 0.01
B. 0.2 to 0.3
C. 2 to 3
D. 5 to 10

Inorganic impurities causing water pollution is ____________________?

A. Fats
B. Carbohydrates
C. Salts of metals
D. Protein

In a sedimentation tank, the detention period for water ranges from _____________ hours?

A. 2 to 4
B. 8 to 12
C. 16 to 20
D. 24 to 32