Sorbitol is a natural laxative that is found in dried plums and is used as the "sugar alcohol" found in some "sugar-free" chewing gums. What is the stereochemical, (R) or (S), configuration of the marked atoms.

The stereochemical configuration of sorbitol is 2S,3R,4R,5R with an S-configuration at the 2-position.  

Explanation:

In the absence of a diagram given of the marked atoms, this is a general information of the stereochemistry of sorbitol. Hopefully it serves as a guide for the answer

The groups attached to the chiral carbons are assigned a priority. Then you should identify the atoms attached to the stereo-centre and priotize them in order of increasing atomic numbers (highest atomic number will take the highest priority 1 and so on). Then take note of the direction in which the priorities decrease (from 1 -2 - 3 - 4 ...). If it decreases in a clockwise manner the stereo-center is labelled as R if it decreases in a counterclockwise manner, the stereo-Centre is labelled as S.

Sorbitol has an IUPAC name called (2S,3R,4R,5R)-hexane-1,2,3,4,5,6-hexol which is based on its stereochemical configuration

Yes it would be a physical change.

C) the increase in atmospheric pressure pushes the walls of the balloon outward thus making it  is the answer.hope i you.