Question:
The orthotolidine test is used for assessing the concentration of which of the following in water?
The orthotolidine test is used for assessing the concentration of which of the following in water?
Show Hint
Think of the yellow colour test done to check residual disinfectant in chlorinated water.
Updated On: Jun 24, 2026
- Chlorine
- Nitrites
- Nitrates
- Fluorine
Show Solution
Verified By Collegedunia
The Correct Option is A
Solution and Explanation
Step 1: The orthotolidine test is a chemical test used in water treatment to measure the amount of residual chlorine present after disinfection.
Step 2: When orthotolidine reagent is added to chlorinated water, free and combined chlorine react with it to produce a yellow colour. The intensity of the yellow colour is directly proportional to the chlorine concentration.
Step 3: This allows estimation of free residual chlorine, which should ideally be at least 0.5 mg/L after a contact period of one hour to ensure safe drinking water.
Step 4: Nitrites, nitrates and fluorine are estimated by other dedicated chemical methods and are not assessed by this test.
Conclusion: The orthotolidine test assesses the concentration of chlorine. The printed answer key (A. Chlorine) is medically correct.
Step 2: When orthotolidine reagent is added to chlorinated water, free and combined chlorine react with it to produce a yellow colour. The intensity of the yellow colour is directly proportional to the chlorine concentration.
Step 3: This allows estimation of free residual chlorine, which should ideally be at least 0.5 mg/L after a contact period of one hour to ensure safe drinking water.
Step 4: Nitrites, nitrates and fluorine are estimated by other dedicated chemical methods and are not assessed by this test.
Conclusion: The orthotolidine test assesses the concentration of chlorine. The printed answer key (A. Chlorine) is medically correct.
Was this answer helpful?
0
0
Top NEET PG Community Science Questions
- Green colour of triage is for which type of patient?
- The Concurrent List of the Indian Constitution includes which of the following?
- The last point up to which the Reproductive and Child Health (RCH) programme is included is:
- The health centre in the remotest area, used as the first contact point for planning and management of schemes, is the:
- The diagnostic power of a test to correctly diagnose a disease (the proportion of positive test results that truly have the disease) is:
View More Questions
Top NEET PG Water Purification - Chlorination Questions
Top NEET PG Questions
- A patient hailing from Delhi presents with fever, arthralgia, and extensive petechial rash for 3 days. Lab investigations revealed a hemoglobin of 9 g/ dL, a white blood cell count of 9000 cells/mm3, a platelet count of 20000 cells/mm3, and a prolonged bleeding time. The clotting time was normal. What is the most likely diagnosis?
- Which of the following statements is true about Trichomonas vaginalis?
- A lady from West Rajasthan presented with an ulcer surrounded by erythema on the right leg. Microscopy of the biopsy from the edge of the ulcer showed organisms with dark staining nuclei and kinetoplast. What is the most likely causative agent?
- A child presents with a fever and a rash. Urine examination showed cells with owl's eye appearance. What is the most likely diagnosis?
- Infection with Clonorchis sinensis is associated with an increased risk of__?
View More Questions