The concentrations of which two ions are highest outside the cell?

Na+ and Cl−

Explanation:

Extra cellular liquid (ECL):

It is the liquid that is outside the cell and that contains the nutrients necessary for the survival of the cells embedded in it.

The ECL contains large amounts of Sodium (Na +), Chloride (Cl -) and Bicarbonate ions. It also contains the nutrients for the cells: oxygen, glucose, fatty acids and amino acids.

Being a liquid surrounding the cell, it contains the debris from the cells being transported to the bloodstream for later disposal.

One third of the total fluid of an adult human corresponds to extracellular fluid.