Answer: polar solvent
Explanation:
Polarity can be said to mean, charge separation. Thus, polar solvents are solvents that have charge separation and the ability to solvate i.e dissolve ions.
A polar solvent molecule has slight electrical charge as a result of its shape. A typical and most common example is water, with an oxygen and two hydrogen atoms. The two hydrogen atoms are at an angle to the single oxygen atom. Water is the classic polar solvent. The oxygen atom tends to polarize electron density to itself.
Pressure has no effect on the solubility of KNO3 in water. This is because it is solid in liquid type of solution. In solid in liquid type of solution, solid is solute (minor component), liquid is solvent (major component). For solid in liquid type of solutions, solubility is independent of pressure.
On other hand, pressure has a pronounced effect on the solubility of gas in liquid type solutions. In such system, gas is solute (minor component) and liquid is solvent (major component). Example of such solution is aerated water. Herein, CO2 is dissolved in water. In such gas in liquid type of solutions, solubility increases with increasing pressure.