The pair of electrolytes that could not be distinguished by the products formed at the electrodes during their electrolysis using inert electrode is..?

@ afrah 
is their any option to this question , 
i guess there will be many electrolytes like that as those electrolyte which cannot be distinguished must not react with the electrode part , 
so, let me know if any option will be their 
WAITING TO HEAR FROM YOU AGAIN