the 3rd one is the answer
Answer:
2
Explanation:
CO₂ shows that there are 2 oxygen molecules. Also, the name Carbon Dioxide. This shows there is One Carbon and Two Oxygen molecules from the naming system.
Answer:
Ordinary table salt is called sodium chloride. It is considered a substance because it has a uniform and definite composition. All samples of sodium chloride are chemically identical. Water is also a pure substance. Salt easily dissolves in water, but salt water cannot be classified as a substance because its composition can vary. You may dissolve a small amount of salt or a large amount into a given amount of water. A mixture is a physical blend of two or more components, each of which retains its own identity and properties in the mixture . Only the form of the salt is changed when it is dissolved into water. It retains its composition and properties.
Homogeneous Mixtures
A homogeneous mixture is a mixture in which the composition is uniform throughout the mixture. The salt water described above is homogeneous because the dissolved salt is evenly distributed throughout the entire salt water sample. Often it is easy to confuse a homogeneous mixture with a pure substance because they are both uniform. The difference is that the composition of the substance is always the same. The amount of salt in the salt water can vary from one sample to another. All solutions would be considered homogeneous because the dissolved material is present in the same amount throughout the solution.
One characteristic of mixtures is that they can be separated into their components. Since each part of the mixture has not reacted with another part of the mixture, the identities of the different materials is unchanged.
According to the Law of Definite Proportions from Dalton's Atomic Theory, each compound is composed of a fixed ratio of each of its individual elements. So, the number of individual elements per 1 particle of that compound is represented by the subscripts. The answers are as follows:
Table sugar: 12 atoms of carbon, 22 atoms of hydrogen; 11 atoms of oxygen; 45 total atoms
Marble: 1 atom of calcium, 1 atom of carbon; 3 atoms of oxygen; 5 total atoms
Natural gas: 1 atom of carbon, 4 atoms of hydrogen; 5 total atoms
Rubbing alcohol: 3 atoms of carbon, 8 atoms of hydrogen; 1 atom of oxygen; 12 total atoms
Table sugar: 1 atom of silicon; 2 atoms of oxygen; 3 total atoms
