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Question: Which of the following radioactive wastes emits all α, β & γ rays and hence is the most hazardous of all radioactive emitters?
[A].

I-131

[B].

Sr-90

[C].

Au-198

[D].

Ra-226

Answer: Option D

Explanation:

No answer description available for this question.

Question: Dose of chlorine for disinfection of water is about __________ mg/litre of water.
[A].

0.01

[B].

0.1

[C].

0.3

[D].

1

Answer: Option D

Explanation:

No answer description available for this question.

Question: Iron & manganese present as pollutant in water can not be removed by
[A].

ion exchange process.

[B].

oxidation followed by settling & filtration.

[C].

lime soda process or manganese zeolite process.

[D].

chlorination.

Answer: Option D

Explanation:

No answer description available for this question.

Question: Iron & manganese present in the polluted water is removed by
[A].

simple filtration.

[B].

oxidation followed by settling & filtration.

[C].

chemical coagulation.

[D].

chlorination only.

Answer: Option B

Explanation:

No answer description available for this question.

Question: Aerobic biological oxidation ponds used for the purification of polluted water
[A].

destroys/removes pathogen from the sewage.

[B].

is not very effective for nonbiodegradable substances (e.g. ABS) containing effluents.

[C].

destroys/removes pathogen much more effectively if the sewage is chlorinated.

[D].

all (a), (b) & (c).

Answer: Option D

Explanation:

No answer description available for this question.

Question: Lagoons used for purification of polluted water
[A].

are large shallow artificial lakes also known as clarification lakes, maturation ponds or oxidation ponds.

[B].

use micro-organisms/bacteria in presence of dissolved oxygen.

[C].

gives an excellent final effluent (with 3 to 4 lagoons arranged in series) having suspended solid < 1 mg/litre and BOD = 3.8 mg/litre.

[D].

all (a), (b) & (c).

Answer: Option D

Explanation:

No answer description available for this question.

Question: Bacterial aerobic oxidation of polluted water in biological oxidation ponds is done to purify it. Presence of bacteria helps in
[A].

coagulation and flocculation of colloids.

[B].

oxidation of carbonaceous matter to CO2.

[C].

nitrification or oxidation of ammonia derived from breakdown of nitrogeneous organic matter to the nitrite and eventually to the nitrate.

[D].

all (a), (b) and (c).

Answer: Option D

Explanation:

No answer description available for this question.

Question: Biological oxidation ponds remove organic matters present in the polluted water by
[A].

using the activities of bacteria and other micro organisms.

[B].

aerobic oxidation.

[C].

both (a) & (b).

[D].

neither (a) nor (b).

Answer: Option C

Explanation:

No answer description available for this question.

Question: Oil and grease present in an emulsified state in waste water discharged from industries can be removed by
[A].

biological oxidation.

[B].

skimming off.

[C].

settling out using chemical reagents.

[D].

chlorination.

Answer: Option C

Explanation:

No answer description available for this question.