Select the species in which the precipitate formed on adding NaOH further dissolves in excess of NaOH.

Question

Infinity Learn · Accepted Answer

(a) $$ZnCl2+2NaOH$$→⟶$$ZnOH2$$↓white $$ppt+2NaClZn(OH)2+2NaOH$$⟶$$Na2ZnO2(soluble$$ sodium $$zincate)+2H2O$$ (b) $$AlCl3+3NaOH$$→⟶$$ZnOH2$$↓white $$ppt+3NaClAl(OH)3+NaOH$$⟶$$NaAIO2(sodium$$ $$metaaluminate)+2H2ONote$$ :$$NaAIO2$$ is also written as $$NaAl(OH)4$$ (c) $$FeCl3+3NaOH$$⟶$$Fe(OH)3$$↓ Brown ppt $$+3NaClFe(OH)3$$ is insoluble in excess of NaOH.  (d) $$CrCl3+3NaOH$$⟶$$Cr(OH)3$$↓ Green ppt $$+3NaCl$$ $$Cr(OH)3$$ is insoluble in excess NaOH. Note :$$Cr(OH)3$$ can be made soluble in NaOH  if $$H2O2Cr(OH)3+2NaOH+H2O2$$⟶$$Na2CrO4$$ Soluble  (yellow) $$+H2OThis$$ is redox reaction.

Select the species in which the precipitate formed on adding NaOH further dissolves in excess of NaOH.

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