➡️Copper and various other transition metals in solution tend to form insoluble hydroxides. This tendency has been used for removing such metals from industrial wastewaters.
➡️Zn 2+ would produce a soluble complex,
If excess sodium hydroxide is added, the precipitate of zinc hydroxide will dissolve, forming a colorless solution of zincate ion: Zn(OH)2 + 2OH- → Zn(OH)42-. This property can be used as a test for zinc ions in solution, but it is not exclusive, since aluminum and lead compounds behave in a very similar manner. Unlike the hydroxides of aluminum and lead, zinc hydroxide also dissolves in aqueous ammonia to form a colourless, water-soluble amine complex.
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ANSWER:-
The answer is 3)Al+3.
➡️Copper and various other transition metals in solution tend to form insoluble hydroxides. This tendency has been used for removing such metals from industrial wastewaters.
➡️Zn 2+ would produce a soluble complex,
If excess sodium hydroxide is added, the precipitate of zinc hydroxide will dissolve, forming a colorless solution of zincate ion: Zn(OH)2 + 2OH- → Zn(OH)42-. This property can be used as a test for zinc ions in solution, but it is not exclusive, since aluminum and lead compounds behave in a very similar manner. Unlike the hydroxides of aluminum and lead, zinc hydroxide also dissolves in aqueous ammonia to form a colourless, water-soluble amine complex.
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