Assertion : Coloured cations can be identifie | vedclass

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Question

(A) Borax $(Na_2B_4O_7 \cdot 10H_2O)$ when heated,loses water and swells up,then melts to form a transparent glassy bead consisting of sodium metabora

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

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(A) Borax $(Na_2B_4O_7 \cdot 10H_2O)$ when heated,loses water and swells up,then melts to form a transparent glassy bead consisting of sodium metaborate $(NaBO_2)$ and boric anhydride $(B_2O_3)$.$Na_2B_4O_7 \cdot 10H_2O$ $\xrightarrow{\Delta} Na_2B_4O_7$ $\xrightarrow{\Delta} 2NaBO_2 + B_2O_3$When this glassy bead is heated with coloured transition metal salts,it forms coloured metaborates,which are characteristic of the metal cation. Thus,the borax bead test is used to identify coloured cations.Since the formation of the transparent bead and its subsequent reaction with cations to form coloured beads explains why the test works,the Reason is the correct explanation of the Assertion.

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

Similar Questions

Indicate the steps in the preparation of:
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$(ii)$ $KMnO_4$ from pyrolusite ore.

Which of the following statements is not correct?

$Cr_2O_7^{2-} \underset{Y}{\overset{X}{\longleftrightarrow}} 2CrO_4^{2-}$,$X$ and $Y$ are respectively

When $MnO_2$ is fused with $KOH$ in the presence of air,a colored compound is formed. Identify the compound and its color.

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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.