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
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
Presence of nitrogen and phosphorous in waste water discharged into lakes and ponds causes_______________?
(A) Foaming
(B) Odour nuisances
(C) Undesirable plant growth
(D) Turbidity
Which of the following is a secondary air pollutant ?
(A) Photochemical smog
(B) Sulphur dioxide
(C) Nitrogen dioxide
(D) Dust particles
Ozone is__________________?
(A) A primary pollutant
(B) A secondary pollutant
(C) Impervious to ultra-violet rays
(D) Both
Infective bacteria in water is killed by the _____________ process?
(A) Sterilisation
(B) Aeration
(C) Disinfection
(D) None of these
Hydrogen ion concentration in distilled water is___________________?
(A) 10-7
(B) 7 × 10-7
(C) 107
(D) 7 × 107
The progressive warming up of the earth’s surface is mainly due to the___________________?
(A) Automobile exhaust
(B) Blanketing effect of CO2 in the atmosphere
(C) De-forestation
(D) Thickening of ozone layer