Chapter 4.1, Problem 3CP

Which of the following compounds is a weak electrolyte?

$\begin{array}{l}\text{a)}\hfill \\ \text{LiCl}\hfill \\ \text{b)}\hfill \\ {\left({\text{C}}_{\text{2}}{\text{H}}_{\text{5}}\right)}_{\text{2}}\text{NH}\hfill \\ \text{c)}\hfill \\ {\text{KNO}}_{\text{3}}\hfill \\ \text{d)}\hfill \\ \text{NaI}\hfill \\ \text{e)}\hfill \\ {\text{HNO}}_{\text{3}}\hfill \end{array}$