Water sample which is likely to contain chlorine. will affect the results of bacteriological analysis of water. %Mich one of the following, if added in small amount in the test tube w ill help overcome it ?
**Core Concept**
Chlorine is a disinfectant commonly used in water treatment to kill bacteria and other microorganisms. However, it also interferes with the bacteriological analysis of water by inactivating or killing the microorganisms being tested for, leading to false-negative results. To overcome this issue, a reducing agent is often added to the water sample to neutralize the chlorine.
**Why the Correct Answer is Right**
The correct answer is a reducing agent that specifically targets chlorine. Sodium thiosulfate is commonly used as a reducing agent to remove chlorine from water samples. It works by converting the chlorine into chloride ions, effectively neutralizing its disinfectant properties. This allows the microorganisms in the water sample to remain viable and unaffected, ensuring accurate results in bacteriological analysis.
**Why Each Wrong Option is Incorrect**
* **Option A:** Sodium hydroxide is a strong base and would not be effective in removing chlorine from water samples. It might even increase the pH, which could affect the growth of certain microorganisms.
* **Option B:** Glucose is a simple sugar and does not have the ability to reduce or neutralize chlorine. It might even provide a nutrient source for some microorganisms, potentially interfering with the analysis.
* **Option C:** Baking soda (sodium bicarbonate) is a mild base and does not have the necessary properties to effectively remove chlorine from water samples.
**Clinical Pearl / High-Yield Fact**
When performing bacteriological analysis of water, it's essential to add a reducing agent like sodium thiosulfate to neutralize chlorine and prevent false-negative results. This is a crucial step in ensuring the accuracy of water quality testing.
**Correct Answer:** C. Sodium thiosulfate.