On addition of cis $1-2$ diol in the aqueous solution of boric acid:

${\mathrm{Ca}}_2{\mathrm{B}}_6{\mathrm{O}}_{11}+{\mathrm{Na}}_2{\mathrm{CO}}_3\stackrel{\mathrm{Fused}}{\to } \left(\mathrm{A}\right)+\left(\mathrm{B}\right)+{\mathrm{CaCO}}_3$

$\left(\mathrm{A}\right)+{\mathrm{CO}}_2\to \left(\mathrm{B}\right)+{\mathrm{Na}}_2{\mathrm{CO}}_3$

$\left(\mathrm{B}\right)+\mathrm{Concentrated} \mathrm{HCl}\to \mathrm{NaCl}+\mathrm{Acid}\stackrel{{\mathrm{H}}_2\mathrm{O}}{\to } \left(\mathrm{c}\right)$

$\left(\mathrm{C}\right)\stackrel{\mathrm{Strongly} \mathrm{heated}}{\to }\left(\mathrm{D}\right)$

$\left(\mathrm{D}\right)+{\mathrm{CuSO}}_4\underset{\mathrm{in} \mathrm{flame}}{\overset{\mathrm{Heated}}{\to }} \mathrm{Blue} \mathrm{coloured} \left(\mathrm{E}\right)$

Compound $\left(\mathrm{A}\right)$ is :

${\mathrm{Ca}}_2{\mathrm{B}}_6{\mathrm{O}}_{11}+{\mathrm{Na}}_2{\mathrm{CO}}_3\stackrel{\mathrm{Fused}}{\to } \left(\mathrm{A}\right)+\left(\mathrm{B}\right)+{\mathrm{CaCO}}_3$

$\left(\mathrm{A}\right)+{\mathrm{CO}}_2\to \left(\mathrm{B}\right)+{\mathrm{Na}}_2{\mathrm{CO}}_3$

$\left(\mathrm{B}\right)+\mathrm{Concentrated} \mathrm{HCl}\to \mathrm{NaCl}+\mathrm{Acid}\stackrel{{\mathrm{H}}_2\mathrm{O}}{\to } \left(\mathrm{c}\right)$

$\left(\mathrm{C}\right)\stackrel{\mathrm{Strongly} \mathrm{heated}}{\to }\left(\mathrm{D}\right)$

$\left(\mathrm{D}\right)+\mathrm{CuSO}4\underset{\mathrm{in} \mathrm{flame}}{\overset{\mathrm{Heated}}{\to }} \mathrm{Blue} \mathrm{coloured} \left(\mathrm{E}\right)$

Compound $\left(\mathrm{B}\right)$ is :

${\mathrm{Ca}}_2{\mathrm{B}}_6{\mathrm{O}}_{11}+{\mathrm{Na}}_2{\mathrm{CO}}_3\stackrel{\mathrm{Fused}}{\to } \left(\mathrm{A}\right)+\left(\mathrm{B}\right)+{\mathrm{CaCO}}_3$

$\left(\mathrm{A}\right)+{\mathrm{CO}}_2\to \left(\mathrm{B}\right)+{\mathrm{Na}}_2{\mathrm{CO}}_3$

$\left(\mathrm{B}\right)+\mathrm{Concentrated} \mathrm{HCl}\to \mathrm{NaCl}+\mathrm{Acid}\stackrel{{\mathrm{H}}_2\mathrm{O}}{\to } \left(\mathrm{c}\right)$

$\left(\mathrm{C}\right)\stackrel{\mathrm{Strongly} \mathrm{heated}}{\to }\left(\mathrm{D}\right)$

$\left(\mathrm{D}\right)+\mathrm{CuSO}4\underset{\mathrm{in} \mathrm{flame}}{\overset{\mathrm{Heated}}{\to }} \mathrm{Blue} \mathrm{coloured} \left(\mathrm{E}\right)$

Compound $\left(\mathrm{C}\right)$ is :

${\mathrm{Ca}}_2{\mathrm{B}}_6{\mathrm{O}}_{11}+{\mathrm{Na}}_2{\mathrm{CO}}_3\stackrel{\mathrm{Fused}}{\to } \left(\mathrm{A}\right)+\left(\mathrm{B}\right)+{\mathrm{CaCO}}_3$

$\left(\mathrm{A}\right)+{\mathrm{CO}}_2\to \left(\mathrm{B}\right)+{\mathrm{Na}}_2{\mathrm{CO}}_3$

$\left(\mathrm{B}\right)+\mathrm{Concentrated} \mathrm{HCl}\to \mathrm{NaCl}+\mathrm{Acid}\stackrel{{\mathrm{H}}_2\mathrm{O}}{\to } \left(\mathrm{c}\right)$

$\left(\mathrm{C}\right)\stackrel{\mathrm{Strongly} \mathrm{heated}}{\to }\left(\mathrm{D}\right)$

$\left(\mathrm{D}\right)+\mathrm{CuSO}4\underset{\mathrm{in} \mathrm{flame}}{\overset{\mathrm{Heated}}{\to }} \mathrm{Blue} \mathrm{coloured} \left(\mathrm{E}\right)$

Compound $\left(\mathrm{D}\right)$ is :

${\mathrm{Ca}}_2{\mathrm{B}}_6{\mathrm{O}}_{11}+{\mathrm{Na}}_2{\mathrm{CO}}_3\stackrel{\mathrm{Fused}}{\to } \left(\mathrm{A}\right)+\left(\mathrm{B}\right)+{\mathrm{CaCO}}_3$

$\left(\mathrm{A}\right)+{\mathrm{CO}}_2\to \left(\mathrm{B}\right)+{\mathrm{Na}}_2{\mathrm{CO}}_3$

$\left(\mathrm{B}\right)+\mathrm{Concentrated} \mathrm{HCl}\to \mathrm{NaCl}+\mathrm{Acid}\stackrel{{\mathrm{H}}_2\mathrm{O}}{\to } \left(\mathrm{c}\right)$

$\left(\mathrm{C}\right)\stackrel{\mathrm{Strongly} \mathrm{heated}}{\to }\left(\mathrm{D}\right)$

$\left(\mathrm{D}\right)+\mathrm{CuO}\underset{\mathrm{in} \mathrm{flame}}{\overset{\mathrm{Heated}}{\to }} \mathrm{Blue} \mathrm{coloured} \left(\mathrm{E}\right)$

Compound $\left(\mathrm{E}\right)$ is: