The poorest conductor of electricity is sucrose.
For substances to conduct electricity in aqueous solution, they must possess charge. Such substances, called electrolytes, are ions.
Sodium chloride dissociates to produce sodium and chloride ions.
Potassium nitrate dissociates to produce potassium and nitrates ions.
Lithium hydroxide, a strong base, dissociates to produce lithium and hydroxide ions
Sulfuric acid, a strong acid, dissociates to produce hydrogen and sulfate ions
Sucrose, is a covalent compound, and not ionic and therefore does dissociate in aqueous solution. It is classified as a no electrolyte.