A pure substance always has the same physical and chemical properties and is either an element or a compound.。（ ）
对
举一反三
- The physical properties are those properties of a substance that can be observed with changing the substance into other substances.
- The physical properties are those properties of a substance that can be observed with changing the substance into other substances. A: 正确 B: 错误
- 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:
内容
- 0
Choose the correct words or phrases to complete the sentences. An element is a substance, the property ____ cannot be changed by any physical means.
- 1
Which analysis indicates whether a particular element or compound is in the sample? A: Qualitative analysis. B: Quantitative analysis. C: Chemical analysis. D: Instrumental analysis.
- 2
Vitamin C helps ease stress from either worry or ______ physical exercise. ( ). A: pure B: considerable C: intense D: tense
- 3
Every element in an array has the same type. A: 正确 B: 错误
- 4
The different stresses used in a compound do not usually affect the meaning of the compound.