Because it contributes to the membrane potential
Think, first, about the type of molecule or formula unit you have (covalent or ionic). In this case, it is a covalent molecule. You start with the carbon. You could say monocarbon, but if it is just said to be carbon it is assumed to be one. Then you take the prefix for 4 and tack it on to the beginning of the chlorine. For this, the name is carbon tetrachloride.
Raising of the boiling point is a colligative property. That means that it depends on the number of particles dissolved. The greater the number of particles the greater the increase in the boiling point. So, you can compare the effect of these solutes in the increase of the boiling point by writing the chemical equations and comparing the number of particles dissolved: 1)ionic lithium chloride, LiCl(s) --> Li(+) + Cl (-) => 2 ions; 2) ionic sodium chloride, NaCl(s) --> Na(+) + Cl(-) => 2 ions; 3) molecular sucrose, C12H22O11 (s) ---> C12H22O11(aq) => 1 molecule; 4) ionic phosphate, Na3PO4 --> 3Na(+) + PO4 (3-) => 4 ions; 5) ionic magnesium bromide, MgBr2 --> Mg(2+) + 2 Br(-) => 3 ions. <span>So, ionic phosphate produces the greatest number of particles and it will cause the greatest increase of the boiling point.</span><span />
