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(A) $I$. In the borax bead test, cobalt oxide reacts with $B_2O_3$ to form cobalt metaborate, $Co(BO_2)_2$, which is blue in color. This statement is

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$I$ & $II$

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(A) $I$. In the borax bead test, cobalt oxide reacts with $B_2O_3$ to form cobalt metaborate, $Co(BO_2)_2$, which is blue in color. This statement is correct.$II$. Diborane $(B_2H_6)$ is prepared by the reaction of sodium borohydride $(NaBH_4)$ with iodine $(I_2)$: $2NaBH_4 + I_2 \rightarrow B_2H_6 + 2NaI + H_2$. This statement is correct.$III$. In diborane $(B_2H_6)$, boron is more electropositive than hydrogen, so the oxidation state of hydrogen is $-1$. This statement is incorrect.$IV$. Boric acid $(H_3BO_3)$ is a weak monobasic Lewis acid, not a tribasic acid, as it accepts $OH^-$ ions from water. This statement is incorrect.Therefore, statements $I$ and $II$ are correct.

Column $I$	Column $II$
$A$. $Bi^{3+} \longrightarrow (BiO)^{+}$	$P$. Heat
$B$. $[AlO_2]^{-} \longrightarrow Al(OH)_3$	$Q$. Hydrolysis
$C$. $SiO_4^{4-} \longrightarrow Si_2O_7^{6-}$	$R$. Acidification
$D$. $(B_4O_7^{2-}) \longrightarrow [B(OH)_3]$	$S$. Dilution by water

The correct statements about the compounds of boron are:
$I$. In borax bead test, the colour of cobalt metaborate is blue.
$II$. Diborane is prepared by the oxidation of sodium borohydride with iodine.
$III$. In diborane, the oxidation state of hydrogen is $+1$.
$IV$. Boric acid is a tribasic acid.

Similar Questions

In diborane $(B_2H_6)$,the two $H-B-H$ bond angles are nearly

If the formula of Borax is $Na_2B_4O_x(OH)_y \cdot zH_2O$,then $x+y+z = ...........$.

The Lewis acid nature of $BX_3$ follows the order:

Match the following:

Column $I$ Column $II$

$A$. $Bi^{3+} \longrightarrow (BiO)^{+}$ $P$. Heat

$B$. $[AlO_2]^{-} \longrightarrow Al(OH)_3$ $Q$. Hydrolysis

$C$. $SiO_4^{4-} \longrightarrow Si_2O_7^{6-}$ $R$. Acidification

$D$. $(B_4O_7^{2-}) \longrightarrow [B(OH)_3]$ $S$. Dilution by water

The correct statement$(s)$ about $B_2H_6$ is/are:

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The correct statements about the compounds of boron are:$I$. In borax bead test, the colour of cobalt metaborate is blue.$II$. Diborane is prepared by the oxidation of sodium borohydride with iodine.$III$. In diborane, the oxidation state of hydrogen is $+1$.$IV$. Boric acid is a tribasic acid.