Assertion : Coloured cations can be identified by borax bead test. Reason : Transparent bead (NaBO?

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p-Block Elements - I

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Assertion : Coloured cations can be identified by borax bead test.

Reason : Transparent bead $(NaBO_2 + B_2O_3)$ forms coloured bead with coloured cation.

If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.

If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.

If the Assertion is correct but Reason is incorrect.

If both the Assertion and Reason are incorrect.

(AIIMS-2009)

Solution

Borax $(Na_2B_4O_7)$ when heated at about $740\,^oC$, forms a glassy bead which gives
different colour beads with different cations. Hence, it is used to identify cations in qualitative analysis. This test is called borax bead test.

$N{{a}_{2}}{{B}_{4}}{{O}_{7}}\,\xrightarrow{740\,{{\,}^{o}}C}\underbrace{\underset{\begin{smallmatrix}
\,\,\,\text{sodium } \\
\text{metaborate}
\end{smallmatrix}}{\mathop{2NaB{{O}_{2}}}}\,\,+\,\,\underset{\begin{smallmatrix}
\text{ boric} \\
anhydride
\end{smallmatrix}}{\mathop{{{B}_{2}}{{O}_{3}}}}\,}_{\text{glassy bead}}$

Standard 11

Chemistry

The tendency to form monovalent compounds among the Group $13$ elements is correctly exhibited in :

easy

(NEET-2017)

The species, having bond angles of $120^o $ is

medium

(NEET-2017)

Select the incorrect statement

$(a)$ $PCl_5$ form weak monobasic acid during hydrolysis
$(b)$ In $B_3N_3H_6$ nucleophile attack on $B-$ atom
$(c)$ $Al_2Cl_6$ is a polar and planar molecule
$(d)$ In $AlF_3$, hybridisation of $Al$ is $sp^2$

hard

The green colour produced in the borax bead test of a chromium$(III)$ salt is due to formation of______:

medium

(IIT-2019)

The $+1 -$ oxidation state in group $-13$ and $+2$ oxidation state in group $-14$ becomes more and more stable with increasing atomic number. Explain.

medium

Assertion : Coloured cations can be identified by borax bead test. Reason : Transparent bead $(NaBO_2 + B_2O_3)$ forms coloured bead with coloured cation.

Solution

Similar Questions

The tendency to form monovalent compounds among the Group $13$ elements is correctly exhibited in :

The species, having bond angles of $120^o $ is

Select the incorrect statement $(a)$ $PCl_5$ form weak monobasic acid during hydrolysis $(b)$ In $B_3N_3H_6$ nucleophile attack on $B-$ atom $(c)$ $Al_2Cl_6$ is a polar and planar molecule $(d)$ In $AlF_3$, hybridisation of $Al$ is $sp^2$

The green colour produced in the borax bead test of a chromium$(III)$ salt is due to formation of______:

The $+1 -$ oxidation state in group $-13$ and $+2$ oxidation state in group $-14$ becomes more and more stable with increasing atomic number. Explain.

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Assertion : Coloured cations can be identified by borax bead test.

Reason : Transparent bead $(NaBO_2 + B_2O_3)$ forms coloured bead with coloured cation.

Select the incorrect statement

$(a)$ $PCl_5$ form weak monobasic acid during hydrolysis
$(b)$ In $B_3N_3H_6$ nucleophile attack on $B-$ atom
$(c)$ $Al_2Cl_6$ is a polar and planar molecule
$(d)$ In $AlF_3$, hybridisation of $Al$ is $sp^2$