What Is Cod Mcq?

Quality and Characteristics of Sewage MCQ Question 4 (i) The COD (Chemical oxygen demand) test is used to measure the content of organic matter of waste water, both biodegradable and non-biodegradble.

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What COD means?

1.1 Chemical Oxygen Demand. COD is an indicative measurement of the amount of oxygen that can be consumed by reactions in a measured solution. It is an indicator of the contents of reducing substances in the water, which are organic, nitrite, sulfide, ferrous salts, etc., and the organic is dominant.

How is COD calculated *?

There is a formula for calculating COD. Consider the formula for COD calculation: (a – b) X C X 8,000 / the volume of the sample in mL. Let “a” represent the titrant used for your sample expressed in mL. Let “b” represent the titrant used for your blank sample in mL.

How is the value of COD compared to BOD Mcq?

Explanation: BOD is the amount of oxygen required to oxidize only organic matter in sewage. It is always less than COD as COD oxidizes both organic and inorganic matter.

What is COD in environmental chemistry?

COD is defined as the amount of oxygen equivalents consumed in the chemical oxidation of organic matter by strong oxidant (e.g., potassium dichromate).

Why is COD important?

In wastewater treatment, the Chemical Oxygen Demand (COD) is an important measurement for the amount of oxygen that is required to break down pollutants (organic substances) in water. The chemical oxygen demand can be measured using different methods, direct or indirect.

What is COD in accounting?

cash on delivery (C.O.D.), also called collect on delivery, a common business term indicating that goods must be paid for at the time of delivery. The payment is usually due in cash but may be made by check if acceptable to the seller. Related Topics: payment delivery mail delivery.

Why do we do COD test?

The COD test is often used to monitor water treatment plant efficiency. This test is based on the fact that a strong oxidizing agent, under acidic conditions, can fully oxidize almost any organic compound to carbon dioxide.

How do you do the COD test?

Test for Chemical Oxygen Demand:

1. Take 10 ml of sample into a round bottom reflex flask.
2. Add some glass beads to prevent the solution from bumping into the flask while heating.
3. Add 1 ml of Mercury sulfate (HgSO₄) solution to the flask and mix by swirling the flask.
4. Add 5 ml of Potassium dichromate (K₂Cr₂O₇) solution.

What is COD water?

Chemical oxygen demand (COD) is the amount of dissolved oxygen that must be present in water to oxidize chemical organic materials, like petroleum. COD is used to gauge the short-term impact wastewater effluents will have on the oxygen levels of receiving waters.

What is difference between BOD and COD?

Biochemical oxygen demand (BOD) is the amount of oxygen required by the microorganisms to break down the organic materials, whereas chemical oxygen demand (COD) is the amount of oxygen required to break down the organic material via oxidation.

What is COD & BOD in water?

The biochemical oxygen demand (BOD) represents the amount of dissolved oxygen (DO) consumed by biological organisms when they decompose organic matter in water. The chemical oxygen demand (COD) is the amount of oxygen consumed when the water sample is chemically oxidised.

What is full form of BOD Mcq?

BOD or Biochemical Oxygen Demand measures the degree of impurity of a water body or sample due to organic matter. BOD is the amount of dissolved oxygen needed by aerobic microbes to breakdown the organic matter present in the water body. So, the correct answer is extend of pollution with organic matter.

What does COD mean in chemistry?

In environmental chemistry, the chemical oxygen demand (COD) is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution.

What chemical is used in COD?

potassium dichromate
COD is measured via a laboratory assay in which a sample is incubated with a strong chemical oxidant for a specified time interval and at constant temperature (usually 2 h at 150°C). The most commonly used oxidant is potassium dichromate, which is used in combination with boiling sulphuric acid.

What can cause COD?

COD increases as the concentration of organic material increases. It also increases if inorganic compounds susceptible to oxidation by the oxidant (typically dichromate) are present. Water with high COD typically contains high levels of decaying plant matter, human waste, or industrial effluent.

What is COD limit?

The chemical oxygen demand (COD) concentration in a treated effluent, if observed to be persistently greater than 250 mg/l before disposal to any receiving body (public sewer, land for irrigation, inland surface water and marine coastal areas), such industrial units are required to identify chemicals causing the same.

What is high COD?

Higher COD levels mean a greater amount of oxidizable organic material in the sample, which will reduce dissolved oxygen (DO) levels. A reduction in DO can lead to anaerobic conditions, which is deleterious to higher aquatic life forms.

What does COD stand for in business?

Collect on Delivery. Shipping, Delivery, Money. Shipping, Delivery, Money. 1. COD.

How does a COD work?

COD is used by senders who want to collect payment for merchandise and/or postage and fees when the item is delivered to the receiver. Sender pays postage plus fees at time of mailing. The mailer guarantees to pay any return postage, unless otherwise specified on the mail. Amount collected may not exceed $1,000.

What does COD mean in law?

Collect on delivery
“Collect on delivery.” These letters are not cabalistic, but have a determinate meaning. They import the carrier’s liability to return to the consignor either the goods or the charges. U. S. Exp. Co.