The device used to determine the density of a liquid by buoyancy is a

The device used to determine the density of a liquid by buoyancy is a

• A. Thermometer
• B. Barometer
• C. Refractometer
• D. Hydrometer

Answer: (D)

When you want to measure density using buoyancy, you rely on how a floating object displaces fluid to balance its weight. A hydrometer is exactly a calibrated float designed for this purpose. It sinks into the liquid until the buoyant force equals its weight, and the depth it sinks depends on the liquid’s density. In denser liquids the hydrometer floats higher, while in lighter liquids it sinks deeper, and the scale on the stem shows the density directly at the liquid’s surface. This direct relationship between submerged volume and density is what makes the hydrometer the appropriate tool for buoyancy-based density measurements. A thermometer measures temperature, which can influence density but does not determine density via buoyancy. A barometer measures atmospheric pressure. A refractometer uses light bending to infer concentration or density in some solutions, but it does not rely on buoyancy.

When you want to measure density using buoyancy, you rely on how a floating object displaces fluid to balance its weight. A hydrometer is exactly a calibrated float designed for this purpose. It sinks into the liquid until the buoyant force equals its weight, and the depth it sinks depends on the liquid’s density. In denser liquids the hydrometer floats higher, while in lighter liquids it sinks deeper, and the scale on the stem shows the density directly at the liquid’s surface. This direct relationship between submerged volume and density is what makes the hydrometer the appropriate tool for buoyancy-based density measurements.

A thermometer measures temperature, which can influence density but does not determine density via buoyancy. A barometer measures atmospheric pressure. A refractometer uses light bending to infer concentration or density in some solutions, but it does not rely on buoyancy.