Question

In borax bead test of ${Co}^{2+}$ the blue colour of bead is due to :

• A. $C{o}_3{B}_2$
• B. $Co{\left(BO2\right)}_2$
• C. $CoO$
• D. none of the above

Answer 1

Answer: (B)

$Co{\left(BO2\right)}_2$

In borax bead test, the colour given by $C{o}^{2+}$ is blue.

$N{a}_2{B}_4{O}_7.10H_{2}O\underset{△}{\overset{}{\to }}2NaB{O}_2+B_2{O}_3+10H_{2}O$

$B_2{O}_3+CoO⟶\underset{\left(Blue\right)}{Co(B{O}_2{)}_2}$