Question

The mineral colemanite is finely powdered and boiled with sodium carbonate solution. The precipitate of $CaC{O}_3$ and other two products X and Y are formed. On passing a current of $C{O}_2,Y$ produces X. Which of the following statement is correct about X?

• A. Oxidation state of boron in compound X is +1
• B. It is used in bead test
• C. It is a black crystaline solid
• D. None of these

Answer 1

The correct option is B It is used in bead test

The mineral colemanite is finely powdered and boiled with sodium carbonate solution.
$C{a}_2{B}_6{O}_{11}+2N{a}_{2}C{O}_3\underset{\left(ii\right)H_{2}O}{\overset{\left(i\right)Fuse}{\to }}2CaC{O}_3\downarrow +\underset{X}{N{a}_2{B}_4{O}_7}+\underset{Y}{2NaB{O}_2}$
On passing current of $C{O}_2$, Y produces X.
$\underset{X}{4NaB{O}_2}+C{O}_2\to \underset{X}{N{a}_2{B}_4{O}_7}+N{a}_{2}C{O}_3\downarrow$
$\underset{X}{N{a}_2{B}_4{O}_7}$ is used in borax bead test.
$\underset{X}{N{a}_2{B}_4{O}_7}\stackrel{\Delta }{\to }2NaB{O}_2+B_2{O}_3\left(\text{glassy bead}\right)$