MCQ Detailed View

Specific gravity is a measure that compares the density of a substance to the density of a reference substance, usually water at 4°C. It is defined as:

Specific Gravity (SG)=Density of the substanceDensity of water\text{Specific Gravity (SG)} = \frac{\text{Density of the substance}}{\text{Density of water}}Specific Gravity (SG)=Density of waterDensity of the substance

Since it is the ratio of two densities, all units cancel out, making specific gravity a dimensionless quantity. This means it has no unit.

For example, if a liquid has a density of 1200 kg/m³ and water has a density of 1000 kg/m³, the specific gravity of the liquid is:

SG=12001000=1.2SG = \frac{1200}{1000} = 1.2SG=10001200=1.2

This value indicates that the liquid is 1.2 times denser than water. Specific gravity is widely used in physics, chemistry, and engineering to compare materials without worrying about units, which makes it convenient for calculations.

Other options, such as Pascal, mass/volume, or none of these, are incorrect. Pascal is a unit of pressure, and mass/volume is a measure of density, not specific gravity. Specific gravity is dimensionless because it is simply a ratio.

Specific gravity is an important concept in everyday science. It helps in identifying substances, designing liquids in industries, and understanding the buoyancy of objects. In practical applications, it is used in hydrometry, material science, and quality control of liquids like oils, chemicals, and beverages.

Understanding that specific gravity has no unit is essential for students to correctly solve physics and chemistry problems and interpret measurements in laboratory and real-life scenarios.