The correct option is (c) 1 and 3 only.
Explanation
Density is a derived physical quantity that measures the compactness of matter. It is a fundamental parameter used to identify substances and determine their behavior in fluids (buoyancy).Statement-wise Analysis
- Statement 1 is Correct: Density is defined as the mass per unit volume of a substance. It is mathematically expressed as $\rho = \frac{m}{V}$, where $m$ is mass and $V$ is volume. The SI unit is $kg/m^3$.
- Statement 2 is Incorrect: The flotation of an object depends on its density relative to the fluid. If the density of an object is less than that of the liquid, it will float. An object sinks only if its density is greater than that of the liquid.
- Statement 3 is Correct: Density is a characteristic property (intensive property) of a substance. This means the density of a pure substance remains constant regardless of its amount or shape under specific conditions of temperature and pressure. For example, the density of a gold coin is the same as that of a gold brick.
Key Takeaway: Density is an intrinsic property of a substance defined as mass per unit volume. It determines buoyancy: objects less dense than a fluid float, while those denser than the fluid sink.