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Right answer is (d) REMOVAL of nitrates, phosphates

For explanation I WOULD say: The tertiary treatment is the STAGE of wastewater treatment in which the water is disinfected chemically or physically prior to discharge into any water body. It involves the removal of nitrates, phosphates, disinfection to reduce the number of microorganisms in the water.

Right answer is (a) Accelerated EUTROPHICATION

Easy explanation: The acceleration in the NATURAL aging process of the lake due to the release of effluents from the industries is known as accelerated or cultural eutrophication. It occurs due to the runoff of FERTILIZERS from the nearby field or increase in the temperature and BOD of the water BODY leading to algal blooms.

The correct CHOICE is (b) By the ACTION of microbes

The best explanation: Also known as the ACTIVE sludge process, in this method, the seed sludge is ADDED to the wastewater for its further breakdown. This happens with the HELP of microbes that consume the remaining organic matter.

Correct answer is (b) Increases

The best I can explain: SOMETIMES there is the ACCUMULATION of certain pollutants (TOXINS) in the tissues of organisms whose concentration increases along the food CHAIN; this process of increasing accumulation of toxins is known as bioamplification or biomagnification. An example is DDT whose concentration increases at each trophic LEVEL.

The correct option is (c) DDT

For explanation: The process of ACCUMULATION of certain POLLUTANTS (toxins) in the tissues of ORGANISMS WHOSE concentration increases along the food chain is known as biomagnification or bioamplification. DDT, methylmercury, toxaphene are examples of such pollutants.

Correct choice is (c) ALGAL BLOOM

For explanation: The microscopic organisms called planktonic algae are the foundation of the AQUATIC food CHAIN in all lakes, ponds, and rivers. However, their excess growth can lead to an algal bloom, choking the SURFACE of any pond or lake.

Correct choice is (d) Bio-magnification

The best EXPLANATION: BIOMAGNIFICATION, ALSO KNOWN as bioamplification is the accumulation of certain pollutants (toxins) in the tissues of organisms whose concentration increases along the food chain. These toxins accumulate in the body because they can’t be digested by organisms.

Right answer is (d) Night

To elaborate: Planktonic algae are MICROSCOPIC organisms and are the foundation of the AQUATIC food CHAIN in all lakes, ponds, and rivers. HOWEVER EXCESS growth can lead to an algal bloom. They utilize the oxygen at night and reduce the dissolved oxygen content.

Correct option is (b) Eutrophication

Explanation: The EXCESSIVE richness of nutrients (phosphorus, nitrates, and detergents) in a lake or other body of water that leads to ACCELERATION in the growth of algae and the NATURAL AGING of the lake is known as eutrophication. Excess algal growth deoxygenates water and reduces the dissolved oxygen CONTENT.

The correct ANSWER is (C) Eutrophication

To explain I would say: The excessive accumulation of nutrients such as phosphorus, NITRATES, and detergents in a LAKE or any other water BODY that leads to the increased productivity of ponds and lakes. This process is known as eutrophication.

The correct option is (d) Death of aquatic animals

The explanation is: The excessive RICHNESS of nutrients in a WATER body leads to an ACCELERATION in the GROWTH of algae and the natural aging of the lake. This EXCESS growth deoxygenates water leading to the death of aquatic life.

Right option is (b) Eutrophication

The EXPLANATION: The excessive richness of nutrients (phosphorus, nitrates, and detergents) in a LAKE or other body of water that leads to acceleration in the growth of ALGAE and the NATURAL aging of the lake is known as eutrophication. Excess ALGAL growth deoxygenates water leading to the death of aquatic life.

Correct ANSWER is (b) Less than 1 PPM

Explanation: The amount of biological oxygen demand in pure drinking water should be less than 1 ppm. Less amount of BOD means more amount of dissolved oxygen (DO) is present in water. This DO is ESSENTIAL for the proper GROWTH of ORGANISMS.

Right option is (d) Below 4 ppm

To explain I would say: The water with the maximum AMOUNT of pollution is known as gravely polluted water. The dissolved OXYGEN does gravely polluted water is below 4 ppm. Very few aquatic ANIMALS can survive in this water.

Right answer is (c) DUMPING of sewage in the water

For explanation: BOD is the dissolved OXYGEN is utilized by microbes in decomposing the organic WASTES of water. The BOD increases when a LARGE amount of sewage is dumped into the water. This lowers the dissolved oxygen CONTENT in water.

Correct answer is (b) 1500mg/liter

Explanation: Biological OXYGEN Demand (BOD) is the dissolved oxygen. It is UTILIZED for decomposing the ORGANIC wastes of water by the microbes. When the amount of BOD is 1500mg/liter, it INDICATES low water pollution.

The correct answer is (a) BIOLOGICAL Oxygen DEMAND and Chemical Oxygen Demand RESPECTIVELY

Easiest explanation: The BOD and COD STAND for the Biological Oxygen Demand and Chemical Oxygen Demand respectively. BOD is the dissolved oxygen is utilized by microbes in decomposing the organic WASTES of water while COD is the measure of the amount of oxygen necessary to oxidize all the pollutants present in water.

The correct ANSWER is (d) Lower dissolved oxygen

The EXPLANATION: The high BOD RESULTS in the reduction of dissolved oxygen in the WATER. This is because the maximum amount of oxygen is utilized by microbes in decomposing the organic wastes of water.

Right OPTION is (b) Algal bloom

The explanation is: The EXCESSIVE growth of planktons in any water body due to the presence of nutrients is KNOWN as an algal bloom. An algal bloom or marine bloom or water bloom is a rapid INCREASE of algae in an AQUATIC system (freshwater as well as marine water).

The correct option is (c) MORTALITY of aquatic creatures

Easy explanation: When the maximum amount of oxygen in the upstream of sewage DISCHARGE is utilized by MICROBES, there is less oxygen availability in the downstream that is rivers, PONDS, or the other water bodies. DUE to this, the aquatic organisms living in that respective ecosystem die due to a deficiency of oxygen.

Correct choice is (b) Microorganisms

For explanation I would say: In the upstream of SEWAGE water, the maximum oxygen is used by the microorganisms. Due to this, there is LESS oxygen availability in the DOWNSTREAM that is rivers, PONDS, or the other water bodies where the fully PROCESSED wastewater is released.

Correct answer is (c) Biological Oxygen Demand

The best I can EXPLAIN: The amount of biodegradable organic MATTER in sewage water ESTIMATED with the help of biological oxygen demand. It is used for indicating the organic strength of wastewater. It is designated as BOD.

Right answer is (d) Bacteria and other MICROBES

For explanation: The degradation of biodegradable organic MATTER present in the domestic sewage is DONE by microbes. They DEGRADE this organic matter and UPTAKE the essential nutrients required for their growth and development.

The correct choice is (c) Domestic waste

For explanation I would SAY: The biodegradable organic matter is a COMPONENT of domestic sewage. The organic compounds present in domestic wastewater are carbohydrates, PROTEINS, and fats (containing carbon, hydrogen, oxygen, NITROGEN, SULPHUR, phosphorus, etc.).

The correct answer is (d) Dissolved salts

The explanation is: The smaller SIZED dissolved MATERIALS are hard to remove from domestic SEWAGE water as they can pass through the filters easily. They contain nutrients such as AMMONIA, calcium, NITRATE, phosphate, and sodium.

The CORRECT option is (B) Solids

For explanation I would say: The large-sized SOLID materials can be easily removed from the polluted water by physical or mechanical MEANS. These can be plastics, metals, sand, ETC.

Right ANSWER is (C) Nutrients

For explanation: These are the smaller size particles that can easily PASS through all the filters hence said as dissolved MATERIALS. They contain various nutrients like ammonia, calcium, NITRATE, phosphate, and sodium.

Correct OPTION is (d) Fecal matter

The BEST explanation: The substances that do not readily dissolve in water but also are not settled down are known as colloidal substances. They may be filtered out in a Gooch Crucible and CONTAINS fecal matter, bacteria, cloth, and PAPER fibers.

The CORRECT option is (b) SAND

For explanation I would say: The suspended solids like sand, clay, and silt are COMMONLY found in domestic sewage. They are the impurities that are visible and do not dissolve in water. They can be removed EASILY by physical or mechanical means.

Correct option is (a) 0.1 percent

The explanation: To make domestic sewage unfit for humans 0.1 percent of IMPURITIES are enough. These 0.1 percent impurities contain dissolved materials (ammonia, nitrate, sodium, ETC.), COLLOIDAL materials (bacteria, cloth, fecal matter, etc.) and suspended SOLIDS (clay, sand, and silt).

Correct option is (a) Burns most efficiently

Easy explanation: CNG (Compressed Natural Gas) preferred over petrol to reduce air POLLUTION. This is because CNG burns most efficiently and very little of it is LEFT UNBURNT. It is CHEAPER than petrol and cannot be easily adulterated.

Correct option is (d) 4

Explanation: Among the 41 most polluted cities of the WORLD DELHI was in the fourth position in the 1990s. This was because it had more cars than the STATES of Gujarat and WEST BENGAL put together.

Right option is (b) 150 dB

Explanation: An UNDESIRED unpleasant loud or high level of sound that causes disturbance is called noise. Almost 150 dB of noise may DAMAGE eardrums thus permanently impairing hearing ability. It may also cause sleeplessness, INCREASED heartbeat, and altered breathing patterns in humans.

The correct ANSWER is (c) Noise

To explain: An undesired UNPLEASANT LOUD or high level of sound that causes disturbance is called noise. It is measured in HERTZ (Hz) which is a derived unit of frequency and is defined as cycles PER second.

Right OPTION is (d) Thermal power plants and SMELTERS

The explanation is: The thermal power plants and smelters release smokestacks. These smokestacks contain PARTICULATE MATTER and various gases containing air pollutants along with harmless gases, such as nitrogen, oxygen, etc.

Correct answer is (d) Scrubber

To explain I would SAY: A scrubber present in an ELECTROSTATIC precipitator can remove gases LIKE sulphur dioxide through a spray of water or lime. It is a component from which the DIRTY air enters in and clean air is released out.

The correct choice is (c) Central POLLUTION Control Board

The best I can explain: Central Pollution Control Board is designated as CPCB. It was FORMED in the year 1974 under the Ministry of Environment, FOREST and Climate Change. It promotes the prevention, control, and ABATEMENT of pollution.

The correct option is (c) Electrostatic precipitator

Easy explanation: The electrostatic precipitator is the most widely USED TECHNIQUE for REMOVING particulate matter as it removes the 99 percent particulate matter present in the exhaust of various industries. It has electrode wires that release electrons that help in attracting the CHARGED dust particles.

Correct OPTION is (c) Reduce growth and YIELD of crops

To EXPLAIN: Air pollution has an adverse EFFECT on crops and plants. They reduce the growth and yield of crops by increasing the rate of premature plant death. This decreases the overall PRODUCTIVITY of an ecosystem.

The correct option is (B) 1986

To explain I would say: The Environment Protection ACT was PASSED by the Government of India in the year 1986. It was passed in order to CONTROL ENVIRONMENTAL (air, water, and soil) pollution.

Right choice is (b) Pollution

Easy explanation: Any undesirable CHANGE in physical, chemical, or biological characteristics of air, land, WATER, or SOIL DUE to the introduction of contaminants into the natural environment is known as pollution. It is also known as ENVIRONMENTAL pollution and affects the environment adversely.