The electrical conductivity of an aqueous solution depends on the concentration of free ions present in it. Hydrochloric acid (HCl) is a strong electrolyte and ionizes almost completely in an aqueous solution to produce a high concentration of $H^+$ and $Cl^-$ ions . Acetic acid ($C_2H_4O_2$) and ammonia ($NH_3$) are weak electrolytes and ionize only partially, resulting in a much lower concentration of ions .

• Fructose ($C_6H_{12}O_6$) is a non-electrolyte and does not produce ions in solution. Therefore, the aqueous solution of HCl will be the best conductor of electric current.