Which pair of reagents reacts to form a tetrahedral complex?
CoCl2(aq)\text{CoCl}_2(\text{aq})CoCl2(aq) and concentrated HCl(aq)\text{HCl}(\text{aq})HCl(aq)
FeSO4(aq)\text{FeSO}_4(\text{aq})FeSO4(aq) and concentrated NH3(aq)\text{NH}_3(\text{aq})NH3(aq)
CrCl3(aq)\text{CrCl}_3(\text{aq})CrCl3(aq) and concentrated NH3(aq)\text{NH}_3(\text{aq})NH3(aq)
CuSO4(aq)\text{CuSO}_4(\text{aq})CuSO4(aq) and sodium ethanedioate(aq)(\text{aq})(aq)