Question

an amount of nitrogen undergoes a physical change and increases its volume. what can be known about this physical change? the boiling point of the nitrogen increased. the mass of nitrogen increased. the color changed. the density changed.

Explanation:

The boiling point is a characteristic property and doesn't change with a simple volume - increasing physical change. In a physical change, mass is conserved, so the mass of nitrogen doesn't increase. Nitrogen is a color - less gas under normal conditions and a volume change doesn't cause a color change. Density is mass per volume ($
ho=\frac{m}{V}$). When volume increases and mass is constant (in a physical change), density decreases.

Answer:

The density changed.