Assertion : Alpha ( ) - amino acids exist as internal salt in sol…

MCQ

Assertion : Alpha $\left( \alpha \right) - $ amino acids exist as internal salt in solution as they have amino and carboxylic acid groups in near vicinity.
Reason : $H^+$ ion given by carboxylic group $(-COOH)$ is captured by amino group $(-NH_2)$ having lone pair of electrons.

✓
If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
B
If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
C
If the Assertion is correct but Reason is incorrect.
D
If both the Assertion and Reason are incorrect.

✓

Answer

Correct option: A.

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

a
All $\alpha $ acids have $-\,NH_2$ and $-\,COOH$ groups. Since $-\,NH_2$ group is basic and $-\,COOH$ group is acidic., in neutral solution it exists as internal salt which is also called as zwitter ion. This zwitter ion is formed due to reason that proton of $-\,COOH$ group is transferred to $-\,NH_2$ group.

$\mathop {\begin{array}{*{20}{c}}
{R\,\,\,\,\,\,\,\,\,} \\
{|\,\,\,\,\,\,\,\,\,\,} \\
{{H_2}\ddot N - CH - COOH}
\end{array}\,}\limits_{\alpha \, - \,amino\,\,acid} $ $\xrightarrow{{In\,\,water}}$

${\begin{array}{*{20}{c}}
{R\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{{H_2}\ddot N - CH - CO{O^ - } + {H^ + }}
\end{array}}$ $\to $ $\underset{\begin{smallmatrix}
Zwitter\,\,ion \\
(dipolar\,\,ion)
\end{smallmatrix}}{\mathop{\begin{matrix}
\,\,\,\,\,\,\,\,\,\,R\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
{{H}_{3}}\ddot{N}-CH-CO{{O}^{-}} \\
\end{matrix}\,}}\,$

Hence assertion and reason both are true and reson is the correct explanation of assertion.

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