Answer :
The dilute NaCl solution has less solute and is typically unsaturated, while the concentrated solution has more solute and may be saturated.
The comparison between dilute and concentrated versions of a NaCl solution can be understood through their saturation levels. A dilute solution of NaCl has less solute dissolved in the solvent, meaning it is unsaturated. For example, when 30.0 g of NaCl is added to 100 mL of water at 20°C, it all dissolves forming an unsaturated solution. In comparison, a concentrated solution has more solute dissolved, and may approach or reach saturation. For instance, at 20°C, adding 40.0 g of NaCl to 100 mL of water results in a saturated solution where 36.0 g of NaCl dissolves and 4.0 g remains undissolved. Here, the concentrated solution has a higher concentration of dissolved NaCl compared to the dilute version.
