A(n) ____________ is a substance that cannot be separated into simpler substances by chemical means.
A: mixtures
B: elements
C: atom
D: molecule
A: mixtures
B: elements
C: atom
D: molecule
C
举一反三
- A chemical is any aspect of a substance which is only seen by means of a chemical reaction (反应).
- To _____ a substance means to produce it by means of chemical or biological reactions. ( ) A: synthesize B: detach C: affix D: attach
- The atomic weight of an atom, or the molecular weight of a molecule, is its mass relative to that of a(n) ________ atom. This is essentially equal to the number of protons plus neutrons that the atom or molecule contains.
- A chemical _______ is any aspect of a substance which is only seen by means of a chemical reaction (反应). A: queries B: property C: obstacles D: margins
- Choose the correct words or phrases to complete the sentences. An element is a substance, the property ____ cannot be changed by any physical means.
内容
- 0
下列（）为聚合物。 A: monomer B: polymer C: molecule D: atom
- 1
What is the most appropriate definition of conformation? A: The chemical formula of a molecule B: The fixed arrangement of atoms dictated by the bonds of a molecule C: The three dimensional structure a molecule is most likely to adopt, given its chemical formula D: The (potentially flexible) spatial arrangement of atoms around fixed bonds in a molecule
- 2
Which of the following substances is not amphoteric substance? A: H2O B: HCO3- C: H2PO4- D: CO32-
- 3
With a chemical r______, a new substance can form.
- 4
A chemical compound that contains two atoms of oxygen and one atom of another chemical element is called ______