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JEE Advanced 2019Paper 1

Exam: JEE Advanced
Year: 2019
Paper: Paper 1
Subject: Chemistry
Chapter: Practical Chemistry

JEE Advanced 2019 · Paper 1 · Chemistry · Practical Chemistry

The green colour produced in the borax bead test of a chromium(III)...

The green colour produced in the borax bead test of a chromium(III) salt is due to -

Options

ACr{ $\left(B{O}_{2}\right)}_{3}$
B $CrB$
CC{r}_{2}{ $\left({B}_{4}{O}_{7}\right)}_{3}$
D $C{r}_{2}{O}_{3}$

Correct answer

A. Cr{ $\left(B{O}_{2}\right)}_{3}$

Step-by-step solution

Borax bead test

{\text{Na}}_{\text{2}}{\text{B}}_{\text{4}}{\text{O}}_{\text{7}}{\text{.10H}}_{\text{2}}\text{O}\overset{\Delta}{\to}{\text{Na}}_{\text{2}}{\text{B}}_{\text{4}}{\text{O}}_{\text{7}}\overset{\Delta}{\to}{\text{NaBO}}_{\text{2}} + {\text{B}}_{\text{2}}{\text{O}}_{\text{3}}

C{r}_{2}{O}_{3} + {B}_{2}{O}_{3}\overset{\Delta}{\to}GreencolouredCr ( B{O}_{2}{)}_{3}

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