Joe Jorgensen
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Water distribution 2 practice test

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Joe Jorgensen
Criado por Joe Jorgensen mais de 6 anos atrás
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Distribution 2 Quiz 3

Questão 1 de 100

1

Which two acids are formed when chlorine gas is mixed with water?

Selecione uma das seguintes:

  • Citric acid and hydrochloric acid

  • Hypochlorous acid and dichloramine

  • Hypochlorous acid and monochloramine

  • Hypochlorous acid and hydrochloric acid

Explicação

Questão 2 de 100

1

Which of the following is a disinfection by-product (DBP)?

Selecione uma das seguintes:

  • Methane

  • Chlorine

  • Trihalomethane

  • Chloramine

Explicação

Questão 3 de 100

1

_____________ is a DBP precursor

Selecione uma das seguintes:

  • Natural organic matter

  • Arsenic

  • Nitrate

  • Lead

Explicação

Questão 4 de 100

1

Which of the following is a velocity meter?

Selecione uma das seguintes:

  • Nutating disk

  • Propeller

  • Piston

  • Compound

Explicação

Questão 5 de 100

1

What is true about a pipe with a C value of 100?

Selecione uma das seguintes:

  • Very smooth interior

  • Very strong pipe

  • Very weak pipe

  • Very rough interior

Explicação

Questão 6 de 100

1

Which of the following is a map that provides an overall view of the entire distribution system, and includes treatment plants, wells, reservoirs, mains, hydrants, and valves?

Selecione uma das seguintes:

  • Combination map

  • Conditional map

  • Comprehensive map

  • Process schematic

Explicação

Questão 7 de 100

1

Which terminology refers to the bottom of a pipe interior?

Selecione uma das seguintes:

  • Invert

  • Crown

  • Lateral

  • Subsurface

Explicação

Questão 8 de 100

1

Which of the following best describes transpiration?

Selecione uma das seguintes:

  • The process by which atmospheric moisture falls onto land

  • The process by which water vapor is released to the atmosphere by living plants

  • The conversion of vapor to liquid

  • The conversion of liquid to solid

Explicação

Questão 9 de 100

1

Choose the best answer regarding coliform sampling.

Selecione uma das seguintes:

  • Samples are taken based on the number of complaints received during the prior month

  • All samples are taken at the largest tank sites

  • Samples must be taken in accordance with an approved sampling plan

  • Samples are taken based on the total length of water main

Explicação

Questão 10 de 100

1

What is the purpose of a venturi?

Selecione uma das seguintes:

  • Measure pH

  • Measure amount of tuberculation in a pipe

  • Measure the water depth in a tank

  • Measure flow rate

Explicação

Questão 11 de 100

1

Which terminology is used to describe the upper surface of an unconfined aquifer?

Selecione uma das seguintes:

  • Borehole

  • Drawdown

  • Water table

  • Zone of influence

Explicação

Questão 12 de 100

1

What must be worn before entering a room with a chlorine gas leak?

Selecione uma das seguintes:

  • Self-contained breathing apparatus (SCBA)

  • Lanyard

  • Harness

  • Cable

Explicação

Questão 13 de 100

1

How are disinfection by-products formed?

Selecione uma das seguintes:

  • Chlorine reacts with arsenic

  • Chlorine reacts with nitrate

  • Chlorine reacts with iron

  • Chlorine reacts with natural organic matter

Explicação

Questão 14 de 100

1

What is true about positive displacement pumps?

Selecione uma das seguintes:

  • It is commonly used to pump groundwater from a well

  • Never operate it with the discharge valve closed because it could rupture the discharge pipe

  • Flow rate varies with change in pressure

  • An impeller is used to move water

Explicação

Questão 15 de 100

1

Which of the following is a strong base?

Selecione uma das seguintes:

  • pH = 6

  • pH = 7

  • pH = 14

  • pH = 1

Explicação

Questão 16 de 100

1

Which of the following is a non-transient, non-community water system?

Selecione uma das seguintes:

  • School

  • Park

  • Motel

  • Restaurant

Explicação

Questão 17 de 100

1

How many feet above the top of a trench must a ladder extend?

Selecione uma das seguintes:

  • At least 5 feet above the top of the trench

  • At least 4 feet above the top of the trench

  • At least 3.5 feet above the top of the trench

  • At least 3 feet above the top of the trench

Explicação

Questão 18 de 100

1

What is the purpose of a pitot gauge?

Selecione uma das seguintes:

  • Test water quality

  • Determine flow rate

  • Test corrosivity of water

  • Check strength of pipe

Explicação

Questão 19 de 100

1

What is true about a fusible plug on a chlorine cylinder?

Selecione uma das seguintes:

  • It is used to remove chlorine from a cylinder

  • It is where chlorine is refilled by an operator

  • It is a safety device that must never be removed

  • It is primarily used to lift the chlorine cylinder

Explicação

Questão 20 de 100

1

What is methemogrlobinemia

Selecione uma das seguintes:

  • Toxic gas

  • Disease caused by lead

  • Ailment caused by coliform

  • Blue Baby Syndrome

Explicação

Questão 21 de 100

1

Which law set the national drinking water standards?

Selecione uma das seguintes:

  • Safe Drinking Water Act

  • Federal Water Act

  • National Potable Water Act

  • Federal Drinking Water Rule

Explicação

Questão 22 de 100

1

Which of the following is true about coliform sampling?

Selecione uma das seguintes:

  • Monthly sampling requirements are based on the total length of service laterals in the distribution system

  • Routine coliform monitoring frequency for a community water system is based on the size of the population served.

  • Monthly sampling requirements are based on the peak demand

  • Monthly sampling requirements are based on the total length of water main in the distribution system

Explicação

Questão 23 de 100

1

__________________ is a type of centrifugal pump.

Selecione uma das seguintes:

  • Plunger pump

  • Piston pump

  • Vertical tubrine pump

  • Diaphragm pump

Explicação

Questão 24 de 100

1

Which of the following is true regarding Tier 2 of the Public Notification Rule?

Selecione uma das seguintes:

  • Customers must be notified as soon as possible, but wtihin 30 days if a contaminant that doesn't pose an immediate health risk exceeds the MCL

  • Customers must be notified within 24 hours if there is potential for human health to be immediately impacted

  • Customers must be notified within a year if a required water sample was not taken

  • Customers must be notified within 48 hours if there is potential for human health to be immediately impacted

Explicação

Questão 25 de 100

1

What is flexural strength of a pipe?

Selecione uma das seguintes:

  • Force required to pull a pipe to the point of failure

  • Compressive force

  • Ability of a pipe to resist tensile force

  • Ability of a pipe to bend without breaking

Explicação

Questão 26 de 100

1

___________________ are types of impeller for a centrifugal pump.

Selecione uma das seguintes:

  • Semi-open and closed

  • Positive and negative

  • Mechanical and packing

  • Cation and anion

Explicação

Questão 27 de 100

1

What is the maximum practical suction lift for a centrifugal pump?

Selecione uma das seguintes:

  • 50 feet

  • Between 1 and 5 feet

  • Between 15 and 25 feet

  • 75 feet

Explicação

Questão 28 de 100

1

What is a Consumer Confidence Report?

Selecione uma das seguintes:

  • An annual report that summarizes the finances of the water purveyor

  • An annual report that projects the water demand for the next five years

  • An annual water quality report to customers regarding their drinking water

  • A bi-annual report that evaluates the reliability of the water system in case of a catastrophe

Explicação

Questão 29 de 100

1

What is back-siphonage?

Selecione uma das seguintes:

  • Backflow from a house with higher water pressure than the adjacent water main

  • Reverse flow from a factory pump to the water distribution system

  • Unprotected connection between a non-potable water source and teh water distribution system

  • Backflow due to negative pressure in the water system

Explicação

Questão 30 de 100

1

What is used to test for leakages in pipes?

Selecione uma das seguintes:

  • Pitot gauge

  • Pressure testing

  • Anode

  • Swab

Explicação

Questão 31 de 100

1

What is a grout seal in a well?

Selecione uma das seguintes:

  • A deal used to minimize water leakage from a well pump

  • The gasket used to connect the well casings to the pump

  • Concrete foundation for the well pump

  • Grout placed outside of the well casing to prevent contamination of the aquifer

Explicação

Questão 32 de 100

1

What will cause a well pump to backspin after pumping has stopped?

Selecione uma das seguintes:

  • Cone of depression

  • Cavitation

  • An open check valve

  • A damaged air release valve

Explicação

Questão 33 de 100

1

____________________ is commonly implemented to resolve taste and odor issues in the water distribution system.

Selecione uma das seguintes:

  • Flushing

  • Adding polymer

  • Adding copper sulfate

  • Injecting sodium thiosulfate

Explicação

Questão 34 de 100

1

What would trigger a Level 1 Assessment for a distribution system that collects at least 40 total coliform samples per month?

Selecione uma das seguintes:

  • More than 10% of samples collected are total coliform positive

  • More than 5% of samples are total coliform positive

  • More than 7% of samples are total coliform positive

  • More than 12% of samples collected are total coliform postive

Explicação

Questão 35 de 100

1

What is residual drawdown?

Selecione uma das seguintes:

  • The difference between the static water level and pumping water level

  • The lowering of the water table by an adjacent well pump

  • If the water level in a well does not return to its original static water level after pumping has stopped, the vertical distance it falls short is the residual drawdown

  • The difference between the ground surface and the pumping water level

Explicação

Questão 36 de 100

1

What problem occurs when the water has low pH?

Selecione uma das seguintes:

  • Scaling

  • High alkalinity

  • Stratification

  • Corrosion

Explicação

Questão 37 de 100

1

What is recover time for a well?

Selecione uma das seguintes:

  • The run time of a well pump

  • The time it takes to cool a well pump

  • The time required for the water level to return to the static water level after pumping has stopped

  • The time it takes to pump the maximum flow rate after the pump has started

Explicação

Questão 38 de 100

1

Which disinfectant is most widely used for a public water system?

Selecione uma das seguintes:

  • Chloramine

  • Chlorine

  • UV

  • Ozone

Explicação

Questão 39 de 100

1

What is the purpose of a coupon in a water distribution system?

Selecione uma das seguintes:

  • Remove tuberculation

  • Check the corrosiveness of water

  • Relieve excess pressure

  • Used to make a hot tap

Explicação

Questão 40 de 100

1

What is a zone of influence for a well?

Selecione uma das seguintes:

  • The area that covers the limits of cone of depression

  • The difference between the static water level and the pumping water level

  • The water level in the well when the pump is operating

  • The water level in the well when the pump has been turned off

Explicação

Questão 41 de 100

1

What is one of the main benefits of repairing a water main while it is pressurized?

Selecione uma das seguintes:

  • Safety of construction employees

  • Helps remove tuberculation

  • Allows crew to check the interior condition of the pipe

  • Minimizes the chances of contaminating the water supply

Explicação

Questão 42 de 100

1

What is the recommended minimum horizontal separation between a new water main and an existing gravity sewer?

Selecione uma das seguintes:

  • 1 foot

  • 5 feet

  • 10 feet

  • 20 feet

Explicação

Questão 43 de 100

1

What must be done if a repeat sample tests positive for total coliform bacteria?

Selecione uma das seguintes:

  • Test sample for Giardia

  • Test sample for E. coli

  • Test sample for Cryptosporidium

  • Test sample for viruses

Explicação

Questão 44 de 100

1

What is dichloramine?

Selecione uma das seguintes:

  • Free residual chlorine

  • A chemical used to dechlorinate water

  • Combined residual chlorine

  • Hypochlorous acid

Explicação

Questão 45 de 100

1

What is used to check for fecal contamination in a water distribution system?

Selecione uma das seguintes:

  • Presence / absence test for coliform bacteria

  • Cryptosporidium test

  • Virus analysis

  • Test for Gieardia

Explicação

Questão 46 de 100

1

What is an appropriative water right?

Selecione uma das seguintes:

  • A water right that is aquired with title to land, bordering surface water

  • A water right that is acquired through adverse possession of someone else's water right

  • A water right for a homeownder who purchased property adjacent to a river

  • A water right that is acquired for the beneficial use of water by following a specific legal procedure

Explicação

Questão 47 de 100

1

What is holding time?

Selecione uma das seguintes:

  • The time it takes to prime a pump

  • Elapsed time between sample collection and analysis

  • The time it takes chlorine to react with ammonia

  • The time it takes to flush a hydrant

Explicação

Questão 48 de 100

1

Which water source is most protected from pathogens?

Selecione uma das seguintes:

  • River

  • Lake

  • Deep well

  • Shallow aquider

Explicação

Questão 49 de 100

1

What is a radial well?

Selecione uma das seguintes:

  • Artesian well

  • Shallow well

  • A pilot well

  • A caisson with horizontally drilled wells

Explicação

Questão 50 de 100

1

What is the purpose of packing in a pump?

Selecione uma das seguintes:

  • Minimize leakage, while allowing a slight leak

  • Completely stop leakage

  • Impart velocity to the water

  • Protect shaft from excessive wear-and-tear

Explicação

Questão 51 de 100

1

What is the purpose of seal water in a pump?

Selecione uma das seguintes:

  • Increase pump pressure

  • Cool and lubricate the packings

  • Cool the motor

  • Clean the impeller

Explicação

Questão 52 de 100

1

What is the purpose of a mechanical seal?

Selecione uma das seguintes:

  • Create a water-tight bell and spigot joint for a pipe

  • Prevent surface water from contaminating the aquifer

  • Connect a new water main to an existing pipe

  • Prevent leakage from a pump

Explicação

Questão 53 de 100

1

Which valve is commonly used in control valves?

Selecione uma das seguintes:

  • Gate valve

  • Globe valve

  • Butterfly valve

  • Air release valve

Explicação

Questão 54 de 100

1

Which terminology means "a sudden change in water pressure, caused by quickly opening or closing a valve?"

Selecione uma das seguintes:

  • Corrosion

  • Tuberculation

  • Water Hammer

  • Cavitation

Explicação

Questão 55 de 100

1

What type of sample should be used to test for bacteria?

Selecione uma das seguintes:

  • Grab sample

  • Composite sample

  • Comprehensive sample

  • Mixed sample

Explicação

Questão 56 de 100

1

_______________ is a condition in which dissolved oxygen is present in water?

Selecione uma das seguintes:

  • Anaerobic

  • Aerobic

  • Thermocline

  • Hydrophobic

Explicação

Questão 57 de 100

1

Which of the following is a secondary containment?

Selecione uma das seguintes:

  • Aresenic

  • Nitrate

  • Manganese

  • Lead

Explicação

Questão 58 de 100

1

What is true about a hydropneumatic tank?

Selecione uma das seguintes:

  • Always sized for fire flow

  • Often used at a water treatment plant to store treated water

  • Typically found in large water systems to provide water via gravity flow

  • Provides inadequate fire protection

Explicação

Questão 59 de 100

1

What is the purpose of a thrust block in a water distribution system?

Selecione uma das seguintes:

  • Stop the flow of water

  • Restrain and prevent movement of the piping system

  • Push air bubbles out of the water main

  • A pump station that adds significant head to the water

Explicação

Questão 60 de 100

1

What is the chlorine residual if the chlorine does is 3.3 mg/L and the chlorine demand is 1.2 mg/l?

Selecione uma das seguintes:

  • 4.5 mg/L

  • 1.2 mg/L

  • 2.2 mg/L

  • 2.1 mg/L

Explicação

Questão 61 de 100

1

Which of the following is a primary contaminant?

Selecione uma das seguintes:

  • Iron

  • Manganese

  • Nitrate

  • Chloride

Explicação

Questão 62 de 100

1

How often should large water meters be tested?

Selecione uma das seguintes:

  • Every 1-4 years

  • Every 5-7 years

  • Bi-Monthly

  • Monthly

Explicação

Questão 63 de 100

1

What is the purpose of using a jumper cable when removing a water meter?

Selecione uma das seguintes:

  • Corrosion control

  • Maintain proper alignment of the service lateral

  • Prevent settling of the meter box

  • Avoid electrical shock

Explicação

Questão 64 de 100

1

How does water temperature affect the effectiveness of chlorine?

Selecione uma das seguintes:

  • Chlorine becomes less effective as the water temperature becomes warmer

  • The higher the temperature, the more rapid the rate of disinfection

  • Water temperature does not impact the effectiveness of chlorine

  • Chlorine effectiveness significantly fluctuates as the water temperature increases

Explicação

Questão 65 de 100

1

What is per capita water usage?

Selecione uma das seguintes:

  • The total amount of water used within a water distribution system each month

  • The total amount of water used by a water district each year

  • Average day demand divided by the total number of people served

  • The total amount of water used by a family in one year

Explicação

Questão 66 de 100

1

Which chemical is commonly used as a liquid disinfectant in the water industry?

Selecione uma das seguintes:

  • Sodium hypochlorite

  • Sodium chloride

  • Sodium hydroxide

  • Calcium hypochlorite

Explicação

Questão 67 de 100

1

What is a volatile substance?

Selecione uma das seguintes:

  • Inorganic matter

  • Organic matter

  • All suspended solids

  • All dissolved solids

Explicação

Questão 68 de 100

1

What could cause water to appear black?

Selecione uma das seguintes:

  • Arsenic

  • Nitrate

  • Manganese

  • Iron

Explicação

Questão 69 de 100

1

What is the purpose of the drain hole in a dry barrel fire hydrant?

Selecione uma das seguintes:

  • Relieve excess pressure

  • Dewater water main prior to repair

  • A drain hole is not commonly found on a dry barrel hydrant

  • Remove water from the barrel of the hydrant

Explicação

Questão 70 de 100

1

What is a composite sample?

Selecione uma das seguintes:

  • A single sample of water collected at a particular time and place

  • A sample to test for pH

  • A collection of individual samples obtained at regular intervals

  • A sample to test for coliform bacteria

Explicação

Questão 71 de 100

1

What is the most common type of water meter for residential services?

Selecione uma das seguintes:

  • Nutating disk water meter

  • Propeller water meter

  • Electromagnetic meter

  • Venturi meter

Explicação

Questão 72 de 100

1

What is the proper way to close a hydrant valve?

Selecione uma das seguintes:

  • Quickly close the valve

  • Slowly close the valve

  • Close the largest valve near the hydrant

  • Close the smallest valve on the adjacent water main

Explicação

Questão 73 de 100

1

What problem would most likely occur if a pump motor is over greased?

Selecione uma das seguintes:

  • Lantern ring is damaged

  • Packings wear out quickly

  • Mechanical seal becomes loose

  • Overheating

Explicação

Questão 74 de 100

1

What is total dynamic head?

Selecione uma das seguintes:

  • Friction loss

  • The difference in water level between the discharge side and suction side of the pump

  • Total static head + head loss

  • The water pressure on the discharge side of the pump

Explicação

Questão 75 de 100

1

What is total static head?

Selecione uma das seguintes:

  • The head on the suction side of the pump

  • The head on the discharge side of the pump

  • Friction loss when the pump is running

  • The vertical distance between the free water surface on the discharge side of the pump and the suction side of the pump

Explicação

Questão 76 de 100

1

Which source water typically contains the most iron and manganese?

Selecione uma das seguintes:

  • Groundwater

  • Lake

  • River

  • Stream

Explicação

Questão 77 de 100

1

What is one of the roles of the attendant during confined space entry?

Selecione uma das seguintes:

  • Authorize entry

  • Assess the conditions inside and outside the confined space to determine if it is safe for the entrant to remain inside, and orders the entrant to evacuate the confined space as necessary

  • Cancel the entry permit, as necessary

  • Verify that all testes specified by the permit have been condcuted and that all procedures and equipment specified by the permit are in place before endorsing the permit

Explicação

Questão 78 de 100

1

What is the source of E. coli?

Selecione uma das seguintes:

  • Intestines of warm-blooded organisms

  • Reptiles

  • Fish

  • Vegetation

Explicação

Questão 79 de 100

1

What will happen if the hydrochloric acid concentration in the water increases?

Selecione uma das seguintes:

  • pH will increase

  • pH will be unaffected

  • pH will significantly fluctuate

  • pH will decrease

Explicação

Questão 80 de 100

1

What is chlorine demand?

Selecione uma das seguintes:

  • The amount of chlorine remaining after contact time

  • Total chlorine dosage

  • The difference between the total chlorine added to the water and the chlorine residual

  • The amount of chlorine injected into water

Explicação

Questão 81 de 100

1

What is used to measure the flow rate of chlorine gas from a cylinder?

Selecione uma das seguintes:

  • Ejector

  • Yoke clamp

  • Fusible plug

  • Rotameter

Explicação

Questão 82 de 100

1

What does pH represent?

Selecione uma das seguintes:

  • Hypochlorite concentration

  • Measure of hydrogen ion activity

  • Hydrogen peroxide concentration

  • Phosphorus and hydrogen concentration

Explicação

Questão 83 de 100

1

What is typically used to measure flow rate in an open channel?

Selecione uma das seguintes:

  • Nutating disk

  • Propeller

  • Weir

  • Positive displacement meter

Explicação

Questão 84 de 100

1

What causes turbidity?

Selecione uma das seguintes:

  • Suspended solids

  • Calcium

  • Sodium

  • Magnesium

Explicação

Questão 85 de 100

1

Why would you not use Lead pipe?

Selecione uma das seguintes:

  • Problem with connecting with pipes of different metals

  • tuberculation issues

  • Turbulence issues

  • Corrosion risks

Explicação

Questão 86 de 100

1

Where is the shut off valve for a dry barrel hydrant?

Selecione uma das seguintes:

  • Top of the hydrant

  • On the lateral

  • within 2 feet of the hydrant

  • Bottom of the hydrant with 2 drain holes

Explicação

Questão 87 de 100

1

How many pounds of pressure on a 9" closed gate valve with a registered 60 psi?

Selecione uma das seguintes:

  • 540 pounds

  • 2543 pounds

  • 3340 pounds

  • 4860 pounds

Explicação

Questão 88 de 100

1

Who determines if a trench needs shoring?

Selecione uma das seguintes:

  • Competent Person

  • Employee in the trench

  • Water Engineer

  • City Official

Explicação

Questão 89 de 100

1

A green paint marking indicates what when excavating a 6 foot trench within 20 feet of a ladder?

Selecione uma das seguintes:

  • Safe to dig here

  • Sewer lines near here

  • 5 feet from the safety of a ladder insertion point

  • Treated water line near here

Explicação

Questão 90 de 100

1

Why would you open a dry barrel hydrant completely

Selecione uma das seguintes:

  • To provide maximum flow

  • To flush the operating nut

  • To provide access to the drain holes

  • To test pH at the next hydrant

Explicação

Questão 91 de 100

1

How would you check the residual pressure of a dry barrel fire hydrant?

Selecione uma das seguintes:

  • Open the hydrant adjacent in the service line

  • Connect a potentiomenter

  • DPD tester

  • Step down test

Explicação

Questão 92 de 100

1

How do you check the level of a chlorine gas cylinder?

Selecione uma das seguintes:

  • Weight it

  • With an injector

  • Wiggle the cylinder

  • With a pressure guage

Explicação

Questão 93 de 100

1

What strength is chlorine gas?

Selecione uma das seguintes:

  • 12.5%

  • 25%

  • 65%

  • 100%

Explicação

Questão 94 de 100

1

White paint markings indicate what?

Selecione uma das seguintes:

  • Water line beneath ground

  • Telecommunications line beneath ground

  • Gas line beneath ground

  • Excavation area

Explicação

Questão 95 de 100

1

What is the residual pressure in reference to measuring a fire hydrant residual pressure?

Selecione uma das seguintes:

  • Pressure reading before water flows.

  • Measurement obtained by a pitot guage on the top of the hydrant

  • Pressure reading while water is flowing (from an outlet other than the flow outlet.)

  • Pressure remaining after all valves have been closed for 60 seconds or more

Explicação

Questão 96 de 100

1

How long do you wait to flush the line after using the tablet method for a new line?

Selecione uma das seguintes:

  • 1 hour

  • 6 hours

  • 24 hours

  • 48 hours

Explicação

Questão 97 de 100

1

Which of the following is best for disinfecting short sections of pipe?

Selecione uma das seguintes:

  • Slug Method

  • Tablet Method

  • Pigging Method

  • Fill Method

Explicação

Questão 98 de 100

1

What is galvanic corrosion?

Selecione uma das seguintes:

  • Galvanized pipe connected to pvc pipe

  • Copper connected to lead pipe

  • Pvc pipe connected to a pump

  • Galvanized pipe with high pH water

Explicação

Questão 99 de 100

1

Which of the following are disinfection types used in water distribution systems

Selecione uma ou mais das seguintes:

  • Calcium Hypychlorite

  • Sodium Hypochlorite

  • Sodium Thiosulfate

  • Chloramine

Explicação

Questão 100 de 100

1

Which are used to dechlorinate water?

Selecione uma ou mais das seguintes:

  • Sodium thiosulfate

  • calcium aerobic

  • ascorbic acid

  • sulfur dioxide

Explicação