Acharacteristic of matter that can be observed without changing the identity of the matter is

A characteristic of matter that can be observed without changing the identity of the matter is a physical property.

Explanation:

A property that does not bring any change in chemical composition of a substance are known as physical properties.

For example, shape, size, mass, volume, density, etc of a substance are all physical properties.

Whereas a property that changes chemical composition of a substance is known as chemical property.

For example, precipitation, reactivity, toxicity etc are chemical property.

A chemical change cannot be reverted back.

Therefore, we can conclude that a characteristic of matter that can be observed without changing the identity of the matter is a physical property.

when it gains or loses electrons