Question: Dissolved oxygen content in river water is around _____________ ppm?

• 1. 5
• 2. 100
• 3. 250
• 4. 500

Question: Direct reaction of unsaturated hydrocarbons with either NO or NO2 produces an eye irritating pollutant compound known as________________?

• 1. Photochemical smog
• 2. Peroxyacetyl nitrate (PAN) or methyl nitrite
• 3. Benzopyrene
• 4. Polyacrylonitrile

Question: Presence of excess fluorine in water causes__________________?

• 1. Dental cavity
• 2. Tooth decay
• 3. Fluorosis
• 4. Respiratory disease

Question: Aerobic biological oxidation ponds used for the purification of polluted water__________________?

• 1. Destroys/removes pathogen from the sewage
• 2. Is not very effective for non-biodegradable substances (e.g. ABS) containing effluents
• 3. Destroys/removes pathogen much more effectively if the sewage is chlorinated
• 4. All A, B & C

Question: TLV of aldrin in public water supply system is about ____________ μg/litre?

• 1. 0.5
• 2. 17
• 3. 357
• 4. 1097

Question: Iron & manganese present in the polluted water is removed by __________________?

• 1. Simple filtration
• 2. Oxidation followed by settling & filtration
• 3. Chemical coagulation
• 4. Chlorination only

Question: BOD of raw municipal sewage may be in the range of about _____________ mg/litre?

• 1. 1-2
• 2. 5-10
• 3. 150-300
• 4. 2000-3000

Question: Tolerable limit of nitrogen oxides in air is _____________ ppm?

• 1. 0.1
• 2. 1
• 3. 5
• 4. 25

Question: Presence of ____________ in water stream are deleterious to aquatic life?

• 1. Soluble and toxic organics
• 2. Suspended solids
• 3. Heavy metals and cyanides
• 4. All A, B & C

Question: Noise emitted by a ventilation fan at a distance of 3 metres is about _____________ decibels?

• 1. 85
• 2. 105
• 3. 125
• 4. 145