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Environmental (241-260)

Updated: Apr 26, 2020

241. The waste stabilization ponds can be

a) aerobic

b) anaerobic

c) facultative



a) B.O.D .... Strength of sewage

b) Methane ... Product of anaerobic decomposition

c) Nitrate ... Methemoglobinemia


243. The following are the sewage treatment processes:

When only preliminary treatment is to be given for sewage, select the required

treatment processes including their correct sequence from the codes given below

1. screening

2. grit removal

When only preliminary treatment is to be given for sewage, select the required

treatment processes including their correct sequence from the codes given below.


244. When was the water (Prevention and Control of Pollution)Act enacted by the

Indian Parliament ? 1974


245. The entry of foul smelling gases into the house coming from the sewers can be prevented by providing water seals for all the fixtures and a vent pipe in the

plumbing system


246. Ringelmann's scale is used to grade density of smoke


247. Eutrophication of water bodies is caused by the excessive discharge of nutrients


248. Non-disposal of solid waste may cause the spread of rodents related plague


249. The following steps are involved in making a spigot and socket joint of cast

iron pipes used in water supply systems :

1. The spigot end is centred into the socket end of the preceding pipe 2. Tarred gasket or hemp yarn is wrapped around the spigot. 3. A jointing ring is placed around the barrel and against the face of the socket. 4. The gasket or hemp yarn is caulked slightly. 5. Molten pig lead is poured and then caulked


250. Match List I (Soil classification of an aquifer) with List II (Values of the range

of hydraulic conductivities in metre per day) and select the correct answer using

•' the codes given below the Lists:

Fine gravel-100 to 1000 Very fine sand- 1 to 10 Silt- 0.1 to 0.01 Pure clay- 10⁻⁵ to 10⁻⁶


251. Which of the following statements about Design Period are true?

1. It is concerned with economy of investments.

2. It takes into account aspects like life and durability and ease or difficulty

of capacity increase of installations.

4. It is concerned with estimating future requirements.


252. A river is the source of water for water supply to a town. Its water is very turbid

and polluted. The correct sequence of steps for treating the river water would be

presedimentation -> prechlorination-> coagulation - sedimentation -filtration -> post-chlorination


253. Uniformity coefficient of filter sand is given by D₆₀/D₁₀


254. Zero hardness of water is achieved by ion exchange method


255. Which of the following statements is/are true in relation to the term 'detention period' in a settling tank ?

1. Greater the detention period, greater the efficiency of removal of settleable matter.

2. It is the time taken for any unit of water to pass through the settling basin.

3. It is usually more than the flow through period



A.Dead-end system-Economy and simplicity B. Grid-iron system-Both economy and reasonably equal pressures C. Ring system-Equal pressures and multiple flow paths D. Radial system-Zonal distribution



A.Hardness-200 mg/l

B. Nitrate concentration-45 mg/l

C. Iron concentration-0.1 mg/l

D. Fluoride concentration-0.5 mg/l



Absence of fluorides- Dental caries Excess of lead- Anaemia Presence of excess nitrates- Methemoglobinaemia Absence of iodide-Goitre


259. Which of the following determinations are not necessary for raw water from a lake for use as source of supply of water for boiler-feed ?

1. Turbidity

2. Iron

3. Hardness


260. Self-cleansing velocity is such flow velocity as would be sufficient to flush out any deposited solids in the sewer

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