Borax Bead Test is carried out when the original mixture is coloured. It is done with the help of a clean platinum wire on which a small loop is made at the end. When borax is heated on platinum wire

Question

Borax Bead Test is carried out when the original mixture is coloured. It is done
with the help of a clean platinum wire on which a small loop is made at the end.
When borax is heated on platinum wire loop a transparent glass like bead is 
obtained. The hot bead is brought in contact with salt till it reacts with fused
borax and colour is imparted to the bead. Bead colour is noted.
Colour of the bead | Ion
1. Blue green | Cu2+
2. Yellow | Fe3+
3. Green | Cr3+
4. Violet | Mn2+
5. Dark blue | Co2+
6. Brown | Ni2+

Prashant Kotian · Accepted Answer

Correct answer: C. Step 1: When NaOH is added to the mixture containing Al3+, Zn2+, and Cu2+, all of them initially form hydroxide precipitates. Step 2: Since Al(OH)3 and Zn(OH)2 are amphoteric, they dissolve in excess NaOH to form soluble aluminate ([Al(OH)4]-) and zincate ([Zn(OH)4]2-) complexes. Step 3: In contrast, Cu(OH)2 is a basic hydroxide and remains insoluble as a characteristic blue precipitate, allowing both the identification and separation of Cu2+ in one step, matching option (c).

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