Instrument used to evaluate specific gravity

• A. Centrifuge
• B. Refractometer
• C. Microscope
• D. Hydrometer

Answer: (B)

Specific gravity reflects how concentrated a fluid is by measuring how solutes affect light or density. A refractometer is the instrument used to evaluate it because it directly measures the refractive index of a small drop of the fluid and converts that into a specific gravity value. This method is fast, requires only a tiny sample, and modern refractometers include temperature compensation for accuracy, which is ideal for routine veterinary tests.

Other instruments do different things. A centrifuge separates components by density, not measure SG. A microscope visualizes cells or crystals, not the overall concentration. A hydrometer can gauge SG by buoyancy but needs more sample, is more sensitive to temperature and clarity, and is less practical for small veterinary samples, which is why the refractometer is preferred.