Which of the following salt is used in borax bead test?

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Solution

The salt which gives borax bead best is the Borax $N a_{2} B_{4} O_{7} .10 H_{2} O$

Borax-bead Test:
Borax reacts with certain metal salts such as $N i^{2} +, C o^{2 +}, C r^{3 +}, C u^{2 +}, M n^{2 +}$ basically transition metal cations, etc., to form colored metaborates. $B O_{2}^{-}$ is known as metaborate. $B_{2} O_{3}$ is glassy transparent bead.
$C r (B O_{2})_{2}$ is green in colour while $C u (B O_{2})_{2}$ is blue in colour.
The colour of the metaborates can be used to identify the metallic ions (cations) in its salts.
$N a_{2} B_{4} O_{7} .10 H_{2} O △ \to - 10 H_{2} O N a_{2} B_{4} O_{7} 740^{\circ} C \to 2 N a B O_{2} + B_{2} O_{3} Glassy mass$
$C u O + B_{2} O_{3} \to C u (B O_{2})_{2} Blue bead$

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Similar questions

N a_{2} B_{4} O_{7} Δ \to 2 N a B O_{2} + B_{2} O_{3}

B_{2} O_{3} + C u O \to C u (B O_{2})_{2}

C u (B O_{2})_{2}

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