RPSC ACF – 2011
⭕ A. Starch iodide method
⭕ B. Orthotolidine method
⭕ C. Both (a) and (b)
⭕ D. None of the above
📚 Explanation:
Residual chlorine in water indicates the amount of chlorine left after disinfection. Several tests are used to check chlorine residuals:
🔹 Orthotolidine test (O.T.)
🔹 D.P.D. test
🔹 Chloroscope test
🔹 Starch–iodide test
Both the orthotolidine method and the starch iodide method are widely used to determine residual chlorine.
Residual chlorine in water indicates the amount of chlorine left after disinfection. Several tests are used to check chlorine residuals:
🔹 Orthotolidine test (O.T.)
🔹 D.P.D. test
🔹 Chloroscope test
🔹 Starch–iodide test
Both the orthotolidine method and the starch iodide method are widely used to determine residual chlorine.
👉 Therefore, the correct answer is: C. Both (a) and (b)
Key Points on Residual Chlorine Tests:
- Orthotolidine test: Traditional method for chlorine detection.
- Starch iodide test: Chlorine oxidizes iodide to iodine, producing visible color.
- DPD test: Modern and accurate colorimetric method.
