Strong or weak electrolytes are very related to strong or weak acids and bases, and this means that the compound will fully dissociate in water or only partially (around 1 to 10%) dissociate, which is the case for weak electrolytes, in the given list, HNO2 can be considered a weak electrolyte, since it will not dissociate 100% in a solution. HNO3 is a strong acid, NaOH is a strong base, NaNO2 is considered to be a weak base, so it could also be considered a weak electrolyte, but we will stick to HNO2, and NaNO3 is known to be a neutral compound. Final answer = HNO2