A pure substance always has the same physical and chemical properties and is either an element or a compound.。（ ）
举一反三
- The physical properties are those properties of a substance that can be observed with changing the substance into other substances.
- To identify a substance, chemists observe two distinct types of , physical and chemical, which are related to physical and chemical that matters undergoes.
- A chemical compound that contains two atoms of oxygen and one atom of another chemical element is called ______
- the quality or state of the chemical substance that has a pH values below 7:
- Choose the correct words or phrases to complete the sentences. An element is a substance, the property ____ cannot be changed by any physical means.