Identify which physical quantity uses the unit kg/m^3 in the S.I. system.

Introduction / Context:
Recognizing units at a glance helps prevent dimensional mistakes in calculations. The unit kg/m^3 appears across materials, soils, fluids, and gases, making it one of the most frequently encountered units in mechanics and civil engineering.

Given Data / Assumptions:

• Density is mass per unit volume.
• kg is the S.I. base unit of mass; m^3 is the S.I. unit of volume.
• Other listed quantities have different S.I. units.

Concept / Approach:
Match each physical quantity with its canonical S.I. unit: force → newton (N), volume → m^3, pressure → pascal (N/m^2), specific weight → N/m^3. Only density correctly matches kg/m^3.

Step-by-Step Solution:

Verification / Alternative check:

Why Other Options Are Wrong:

Common Pitfalls:

Final Answer: