Because a 50 50 solution of equal concentrations of acid and base neutralize each other and you will get basically a complete neutral substance like water
Light and sound aren't matter because Photons have no mass.
Answer is: <span>because dissolved compounds can crystallizing from solution during filtration and forming crystals on the filter paper or funnel.
</span>Recrystallization<span> is a technique used to purify chemicals by dissolving both impurities and a compound in an appropriate solvent, either compound or impurities can be removed from the solution, leaving the other behind.</span>
