Environmental Engineering

181.Sound produced by an automobile horn heard at a distance of 1.5 metres corresponds to about _________ decibels.

1. 90
2. 120
3. 150
4. 180

182.Sulphur dioxide present in the industrial chimney exhaust gases causes

1. Respiratory&lung disease
2. Reduction in plant's productivity owing to acid rain
3. Corrosion of building materials
4. All (A), (B) and (C)

183.Suspended solid present in the waste water generated in blast furnace gas cooling and cleaning plant is removed by

1. Biological oxygen pond
2. Radial settling tank (thickener) using coagulant (lime&ferrous sulphate)
3. Lagoons
4. Filtration

184.The amount of chemical coagulant added for treatment of polluted water _________ with increase in temperature of the polluted water to be treated.

1. Decreases
2. Increases
3. Remain constant
4. May increase or decrease; depends on the chemical characteristics of polluted water

185.The average thickness of ozone layer in stratosphere is about _________ dobson unit (DU).

1. 20
2. 230
3. 750
4. 1500

186.The biological decomposition of organic substances in wastes controlled conditions is called

1. Incineration
2. Biological oxidation
3. Composting
4. None of these

187.The common pollutant generated in chlor-alkali industry and battery manufacture is

1. Mercury
2. Brine
3. Phosphate
4. None of these

188.The concentration of water vapour in troposphere, which depends upon the altitude & temperature, varies in the range of zero to _________ percent.

1. 1
2. 4
3. 8
4. 12

189.The density of the gases (present in air) decreases with increasing altitude to such an extent, that about 70% of the mass of atmospheric air is found in the lower 5 km. of the atmosphere. his lower region of atmosphere is called the

1. Ionosphere
2. Troposphere
3. Stratosphere
4. None of these

190.The destruction of water-borne pathogens is termed as disinfection of water. Which of the following is a water disinfectant?

1. Chlorine
2. Alkalis
3. Benzene hexachloride
4. Alkyl benzene sulphonate (ABS)