Hydrolysis of $\mathrm{BCl}_{3}$ gives $\mathrm{X}$ which on treatment with sodium carbonate produces $\mathrm{Y}, \mathrm{X}$ and $\mathrm{Y}$, respectively, are

• A

  $\mathrm{H}_{3} \mathrm{BO}_{3}$ and $\mathrm{NaBO}_{2}$
• Correct answer
  B

  $\mathrm{H}_{3} \mathrm{BO}_{3}$ and $\mathrm{Na}_{2} \mathrm{~B}_{4} \mathrm{O}_{7}$
• C

  $\mathrm{B}_{2}^{\circ} \mathrm{O}_{3}$ and $\mathrm{NaBO}_{2}$
• D

  $\mathrm{B}_{2} \mathrm{O}_{3}$ and $\mathrm{Na}_{2} \mathrm{~B}_{4} \mathrm{O}_{7}$

Hence, the correct answer is option: 'B'.