2. which of the following substances is the most soluble in water?
carbon
sodium chloride
bromine
methane

Sodium Chloride is the most soluble substance in water.

B

Explanation

The substance which can be most soluble in water states that the resultant will be formed as a solution.

In that solution, water will act as solvent and the substance which can be soluble in water will be termed as solute.

Any substance will be soluble or not in a solvent can be determined by the nature of the solute and solvent.

It is known that compounds can be classified as polar and non polar substances.

The polar substances are the one which have higher electronegative differences between the elements in that substance and hence mostly ionic bond compounds fall under polar solvents.

The non polar solvents are the one which did not have much difference in their electronegativities.  

It is also known that if the solute and solvent have similar nature, then they can dissolve easily.

So in this case water is a polar solvent and among the choices given, sodium chloride is also a polar solvent.

Thus sodium chloride is the most soluble in water as the remaining substances are non polar in nature.

pure substance: iron,copper

impure substance: water,charcoal