What is a characteristic of a substance that can be observed without changing the identity of the substance?
Physical characteristics of a substance can be observed without changing its identity. In comparison, chemical characteristics require a change in material's identity. These are also known as physical or chemical changes. Examples of physical characteristics include, density, mass, volume, etc. We can measure each of these properties without causing any change in the material (for example, mass can be measured by a weighing scale, volume can be measured by water displacement, etc.).On the other hand, when we talk about properties such as heat of combustion (amount of heat generated when a substance burns in presence of oxygen) or radioactivity (disintegration of unstable nucleus by release of emissions and formation of atoms with lower atomic numbers), etc., we are discussing chemical properties (since the composition of the material is changing).
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