Environmental Studies · General Awareness

Water Quality and Pollution

1,303 Questions

Water Quality and Pollution examines the sources, mechanisms, and impacts of contaminants in aquatic ecosystems. It covers crucial environmental concepts like eutrophication, biochemical oxygen demand, and thermal pollution. This subject frequently appears in general science and environmental studies sections of various examinations.

Eutrophication CausesThermal Pollution EffectsBiochemical Oxygen DemandSynthetic Fertilizer ImpactsWastewater SourcesAquatic Ecosystem Toxicity

Water Quality and Pollution Questions

Multiple choice chemistry water too little to waste pollution of water water pollution planet earth

Which of the following statement is false?

  1. Lower the concentration of D.O., the more polluted is the water sample
  2. The tolerable limit of lead in drinking water is $50\ ppm$
  3. Water is considered pure if it has BOD less than $5\ ppm$
  4. In COD determination, the pollutants resistant to microbial oxidation are not oxidized by an oxidizing agent like $K _{2}Cr _{2}O _{7}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In COD, the degradation is affected by an oxidizing agent, $K _2 Cr _2 O _7.$ COD  is a measure of amount of oxygen , required to degrade or breakdown the organic matter. 

Multiple choice chemistry water too little to waste pollution of water water pollution planet earth

Biochemical Oxygen Demand (BOD) is a measure of organic material present in water. BOD value less than 5 ppm indicates a water to be ________.

  1. rich in dissolved oxygen

  2. poor in dissolved oxygen

  3. highly polluted

  4. not suitable for aquatic life
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Clean water has BOD which is less than 5 ppm. If it is equal to or more than 12 ppm, then the water is considered as polluted. So this indicates water be rich in dissolved oxygen, that helps the microorganisms to oxidize inorganic and organic materials. 

Multiple choice chemistry water too little to waste pollution of water water pollution planet earth

Pollution of lakes and rivers affects aquatic life. Fish cannot live in water that has oxygen less than $4$ milligrams per liter. Other freshwater aquatic life (including anaerobic bacteria) also cannot survive without adequate oxygen. 'BOD' stands for:

  1. Biological oxygen demand

  2. Bacterial oxygen deficit

  3. Basic oxygen demand

  4. Building oxygen deposits
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
BOD stands for Biological Oxygen Demand is the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at a certain temperature over a specific time period.
Multiple choice chemistry water too little to waste pollution of water water pollution planet earth

Clean water would have Biochemical oxygen demand (BOD) value of less than:

  1. 17 ppm

  2. 5 ppm

  3. 200,000 ppm

  4. 10 ppm
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
A water supply with a BOD level of 3-5 ppm is considered moderately clean. In water with a BOD level of 6-9 ppm, the water is considered somewhat polluted because there is usually organic matter present and bacteria are decomposing this waste.
Hence, clean water would have a BOD value of less than 5.

Hence, the correct option is $\text{B}$
Multiple choice chemistry water too little to waste pollution of water water pollution planet earth

Biological Oxygen Demand (BOD) can be defined as:

  1. the amount of oxygen required by bacteria to break down the organic matter of a sample of water

  2. the amount of chemicals required to break down the organic matter of a sample of water

  3. the amount of phosphate required to oxidise the organic matter of a sample of water

  4. the amount of organic matter present in the given sample of water
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

BOD refers to the dissolved oxygen that the microorganisms like bacteria need to oxidize, means to break down inorganic and organic matter in water. It is a measure of water quality. 

Multiple choice chemistry water too little to waste pollution of water water pollution planet earth

What does $BO{D} _{5}$ represent?

  1. Biological oxygen demand in five days

  2. Dissolved oxygem left after five days

  3. Dissolved oxygen consumed in five days

  4. Microorganisms killed by ozone in sewage treatment plants in five hours
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$BO{ D } _{ 5 }$ stands for 5-day Biochemical Oxygen Demand. The BOD test measures, oxygen is used as microbes breathe as they eat the contaminants  in wastewater.

Multiple choice chemistry water too little to waste pollution of water water pollution planet earth

10 mL of water required 1.47 mg of $K _{2}Cr _{2}O _{7}$ (M. wt. = 294) for oxidation of dissolved organic matter in presence of acid. Then the C.O.D of water sample is:

  1. 2.44 ppm

  2. 24 ppm

  3. 32 ppm

  4. 1.6 ppm
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$ Number \  of   \ milliequivalent $ = $\dfrac{weight \ in \ mg}{Equivalent\  weight}$


= $\dfrac{1.47}{294/6}$ = $0.03meq$

$\therefore$COD of sample is:

$\dfrac{0.03}{10}\times 1000$ =  $3meq/L$

In terms of Oxygen COD is :

$3 meq/L \times  (8 mg O _2/meq)$ = $24 mg/L= 24ppm$

Option B is correct.

Multiple choice evs sources of water the lithosphere and the hydrosphere first aid safety and first aid

Biochemical Oxygen Demand (BOD) in a river water :

  1. Increases when sewage gets mixed with river water

  2. Remains unchanged when algal bloom occurs

  3. has no relationship with concentration of oxygen in the water

  4. Gives a measure of Salmonella in the water
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

BOD measures the amount of oxygen required by aerobic microorganisms to decompose organic matter. Sewage contains high levels of organic matter, which increases microbial activity and thus increases BOD.

Multiple choice

What is the primary challenge associated with the maintenance of permeable pavements?

  1. Clogging of pores and reduced infiltration capacity

  2. Increased susceptibility to cracking and damage

  3. Higher cost of construction and maintenance

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Clogging of pores due to sediment and debris accumulation is a common challenge in the maintenance of permeable pavements, as it can reduce the infiltration capacity and effectiveness of the pavement.

Multiple choice

Which of the following is a potential challenge associated with the construction of permeable pavements?

  1. Higher cost compared to traditional pavements

  2. Increased complexity of design and installation

  3. Limited availability of suitable materials

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Permeable pavements may involve higher costs, increased complexity of design and installation, and limited availability of suitable materials compared to traditional pavements.

Multiple choice

What is the primary cause of eutrophication in water bodies?

  1. Excess nutrients (nitrogen and phosphorus)

  2. Industrial pollution

  3. Deforestation

  4. Climate change
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Eutrophication is a process in which a water body becomes enriched with nutrients, particularly nitrogen and phosphorus. This can lead to excessive growth of algae and other aquatic plants, which can deplete oxygen levels and harm aquatic life.

Multiple choice

What is the term for the process by which water quality is improved through natural processes?

  1. Bioremediation

  2. Phytoremediation

  3. Natural attenuation

  4. Self-purification
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Self-purification is the process by which water quality is improved through natural processes such as dilution, sedimentation, and biological degradation. This process can help to remove pollutants and restore the balance of aquatic ecosystems.