An engineer plans chlorination of an open well in a village and needs to determine the exact dose of bleaching powder required. The field apparatus designed for this purpose is:

• A Orthotolidine comparator
• B Chloroscope
• C Berkefeld filter
• D Horrock's apparatus ✓

Explanation

Horrock's apparatus is a simple field device consisting of black cups of graduated capacity used to estimate the chlorine demand of water, so that the correct quantity of bleaching powder can be calculated before disinfection. D chloroscope is used afterwards to measure residual chlorine, not to determine the dose. The orthotolidine comparator also tests residual chlorine colorimetrically. Berkefeld is a candle filter for purification, unrelated to dosing.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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