MCQ
Which compound does not give positive test in Lassaigne's test for nitrogen?
- AUrea
- BHydrazine
- CAzobenzene
- DPhenyl hydrazine
Explanation:
In Lassaigne's test, the organic compound is fused with sodium.
Carbon and nitrogen present in the organic compound gives sodium cyanide (NaCN).
This is further used in the test for nitrogen.
Hydrazine (H2N − NH2) do not contain carbon. It cannot form NaCN on fusion with sodium.
Hence, hydrazine cannot give Lassaigne's test for nitrogen.
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Product $(B)$ of above the reaction is
Which of the following cation does not respond to the above reaction ?
$\mathop {\begin{array}{*{20}{c}}
{\begin{array}{*{20}{c}}
{COOH\,\,} \\
{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{H - C - OH\,\,\,\,\,\,\,\,\,\,\,} \\
{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}
\end{array}} \\
{Br - C - H\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{\,\,\,COOC{H_3}}
\end{array}}\limits_{(I)} $ $\mathop {\begin{array}{*{20}{c}}
{\begin{array}{*{20}{c}}
{\,\,\,\,\,\,\,\,COOC{H_3}\,\,} \\
{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{H - C - Br\,\,\,\,\,\,\,\,\,\,\,} \\
{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}
\end{array}} \\
{HO - C - H\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{\,\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{\,\,\,\,\,\,\,COOH\,\,\,\,\,\,\,\,}
\end{array}}\limits_{(II)} $
Assertion $A$: $\mathrm{pK}_{\mathrm{a}}$ value of phenol is $10.0$ while that of ethanol is $15.9$.
Reason $R$: Ethanol is stronger acid than phenol.In the light of the above statements, choose the correct answer from the options given below: