Question

$C{a}_2{B}_6{O}_{11}+N{a}_{2}C{O}_3\stackrel{△}{\to }\left[X\right]+CaC{O}_3+NaB{O}_2$
Correct statement(s) is/are:

• A. Structure of anion of crystalline [X] has one boron atom $s{p}^3$ hybridized and other three boron atoms $s{p}^2$ hybridized
• B. [X] with $NaOH(aq.)$ gives a compound which on reaction with hydrogen peroxide in alkaline medium yields a compound used in cleaning
• C. Hydrolysis of [X] with $HCl$ or $H_{2}S{O}_4$ yields a compound which on reaction with $HF$ gives fluoroboric acid
• D. Aqueous solution of [X] has pH more than 7

Answer 1

Answer: (B), (C), (D)

The correct options are
B [X] with $NaOH(aq.)$ gives a compound which on reaction with hydrogen peroxide in alkaline medium yields a compound used in cleaning
C Hydrolysis of [X] with $HCl$ or $H_{2}S{O}_4$ yields a compound which on reaction with $HF$ gives fluoroboric acid
D Aqueous solution of [X] has pH more than 7

$C{a}_2{B}_6{O}_{11}+N{a}_{2}C{O}_3\stackrel{△}{\to }N{a}_2{B}_4{O}_7+CaC{O}_3+NaB{O}_2$
[X] is borax.

(a) Structure of anion of crystalline [X] has two boron atom $s{p}^3$ hybridized and other two boron atoms $s{p}^2$ hybridized.
(b) $N{a}_2{B}_4{O}_7+NaOH⟶NaB{O}_2+H_{2}O$
$NaB{O}_2+H_2{O}_2⟶NaB{O}_3.H_{2}O$
Sodium perborate monohydrate $(NaB{O}_3.H_{2}O)$ is used for cleaning purposes.
(c) Hydrolysis of borax with $HCl$ or $H_{2}S{O}_4$ gives boric acid which on reaction with $HF$ gives fluoroboric acid.

Na₂B₄O₇·10H₂O + 2 HCl → 4 B(OH)₃ + 2 NaCl + 5 H₂O
H₃BO₃ + 4HF → H[BF₄] + 3H₂O
(d) Aqueous solution of borax is alkaline in nature.