16. You are running a TLC plate with a polar (A) and nonpolar substance (B); your solvent is a hexane and dichloromethane mixture (1:1). Substance B is traveling up the plate, but substance A has not traveled at all. What solvent might you add to the solvent mixture for substance A to move up the plate

Acetone

Explanation:

Chromatography has to do with the separation of substances by eluting the components of the solute using a mobile phase. The composition of the mixture to be separated decides the mixture of solvents (mobile phase) that are to be used for elution.

In this case the mixture to be separated comprises of substance A which is polar and substance B which is non polar. It is observed that the mobile phase moves B up the plate but not the polar substance, A. This means that a polar solvent such as acetone should be added to the mobile phase in order to achieve better elution of A.

it's all four options.

aquifers are bounded above and below by impermeable rock. the driving force of groundwater movement in confined aquifers is pressure, rather than gravity.