Answer:-
H2SO3 (aq)
Explanation:-
NaCl, KOH and HCl ionic compounds.
Ionic compounds dissociate into ions in water.
Ions can carry electricity in water. So NaCl, KOH and HCl are all strong electrolytes.
H2SO3 is not a strong acid and dissociates to a small extent into ions in water.
Hence number of ions formed is less. Hence it is a weak electrolyte.