A <em>solution </em>is constituted by two parts: thesoluteand the solvent (there may be more than 1 solute and more than 1 solvent, but that is not the key of the answer).
<em>Solute</em> is the substace that is dissolved and it is in less amount than the solvent.
<em>Solvent</em> is the substance that can dissolve the solute and it is a greater amount than the solute.
In the given solution:
<em>sodium fluoride</em>, <em>85.0 mL</em>, is the solute,
<em>water</em>, <em>350.0 mL</em> is the solvent, and
