When sodium chloride is dissolved in water, the polar water molecules are able to work their way in between the individual ions in the lattice. The water molecules surround the negative chloride ions and positive sodium ions and pull them away into the solution. This process is called dissociation.
Independent ( because the reading relies on the different cuffs ) making this a reliable yet invalid experiment. It’s reliable because it consistently differed by 15 points each different cuff. Invalid because the readings were constant with the correct cuff, putting the incorrect cuff size can cause inaccurate readings