The lack of a number preceding the carbon symbol C and the compound formula CO2 shows that there is one carbon atom and one carbon dioxide molecule. Subscript numbers in chemical formulas represent the number of atoms or molecules immediately preceding the subscript.
Carbon is special and unique because it is able to form different compounds with a lot of elements, including itself. When it bonds with itself, this is possible because of the concept of hybridization. It is the mixing of atomic orbitals into a new hybrid orbital. In this case, methane is formed through the sp³ hybridization.
A seperation method that would be most successful woth the separation of a salt and water mixture would be evaporation for these reasons, (1) There are no magnetic elements involved with salt nor with water, (2) Observing colour differences would not have much affect on separating the two, and (3) Chromatography is used to separate two liquids, such as speparating two dyes, not salt and water.
Evaporation:
The water will evaporate, leaving you with salt as a solid.
Answer: 19
Explanation:
In order to write the Potassium electron configuration we first need to know the number of electrons for the K atom (there are 19 electrons). When we write the configuration we'll put all 19 electrons in orbitals around the nucleus of the Potassium atom.