Final answer:
Option 1, 'The mass of the metal cylinder is 7.0 g/cm3', is a quantitative observation because it specifies the metal cylinder's density. The concept of density involves specific measurements, as in the example where a 240-g rock displacing 89.0 cm³ of water has a density of 2.70 g/cm³.
Step-by-step explanation:
An example of a quantitative observation is an observation that includes a measurable quantity, such as weight, length, or temperature. Option 1, stating 'The mass of the metal cylinder is 7.0 g/cm3', is a quantitative observation because it provides a specific measurement of density, which is a measured mass per unit volume. To illustrate, if we take a 240-g rock that displaces 89.0 cm³ of water, we calculate its density by dividing the mass by the volume; thus the density of the rock is 2.70 g/cm³. This is consistent with the definition that density is a measure of mass per unit volume. Density is a key concept in science, particularly in chemistry and physics, because it relates to buoyancy and can help in identifying substances. For instance, materials like oil that are less dense than water will float, while denser substances like metals will sink. This is evident in the case of common substances like wood and brass, where wood floats because it has a lower density than water, and brass sinks due to its higher density. These concepts clearly demonstrate the quantitative nature of density as a physical property.