Question

Arrange the following flotation solutions in increasing order on the basis of their specific gravity:
(A) Saturated Sodium Chloride solution
(B) Saturated Zinc Sulphate solution
(C) Sheather's sugar solution
(D) 35% Magnesium sulphate solution
Choose the correct answer from the options given below:

• A. (A), (C), (D), (B).
• B. (A), (B), (C), (D).
• C. (B), (A), (D), (C).
• D. (C), (B), (D), (A).

Hint:

To easily remember the specific gravity order: Zinc Sulphate is the lightest at 1.18 (ideal for fragile protozoan cysts like Giardia), Salt is in the middle at 1.20, and viscous Sugar is the heaviest at 1.27.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Flotation is a diagnostic technique in veterinary parasitology used to concentrate and isolate parasitic eggs, oocysts, and cysts from fecal debris based on their specific gravity.
For flotation to be successful, the specific gravity of the flotation solution must be higher than that of the parasitic elements, allowing them to float to the surface.

Step 2: Detailed Explanation:
Let us review the standard specific gravities of the common flotation solutions:
- Saturated Zinc Sulphate ($ZnSO_4$) solution (B): The standard specific gravity used for diagnostic fecal flotation is typically adjusted to 1.18 (saturated solutions can range up to 1.20). This is the lowest specific gravity among the listed options.
- Saturated Sodium Chloride (NaCl) solution (A): A fully saturated solution of common salt has a specific gravity of approximately 1.20.
- 35% Magnesium Sulphate ($MgSO_4$) solution (D): This solution has a specific gravity of approximately 1.24 to 1.28.
- Sheather's sugar solution (C): This highly viscous sucrose-based solution has a standard specific gravity of 1.27 to 1.30 (and can be prepared up to 1.33), making it the highest specific gravity solution among the options.
Arranging these solutions in increasing order of their specific gravity yields: \[ \text{Saturated Zinc Sulphate (B) [1.18]} < \text{Saturated Sodium Chloride (A) [1.20]} < \text{35% Magnesium Sulphate (D) [1.24]} < \text{Sheather's Sugar (C) [1.27]} \] This corresponds to the sequence (B), (A), (D), (C).

Step 3: Final Answer:
The correct increasing order is (B), (A), (D), (C), corresponding to option (C).