During a field visit, a medical officer needs to determine the exact dose of bleaching powder required to chlorinate an open dug well. Which instrument is specifically designed for this purpose?
- A Horrock's apparatus ✓
- B Berkefeld filter
- C Orthotolidine arsenite kit
- D Nessler's cylinder
Correct answer: A. Horrock's apparatus
Explanation
Horrock's apparatus is a simple field device consisting of white cups used to find the chlorine demand of well water and calculate the bleaching powder dose needed for satisfactory chlorination. Orthotolidine tests only measure residual chlorine already present, they do not determine the required dose. Berkefeld is a household candle filter and Nessler's reagent detects ammonia, so neither serves this purpose.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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