The exact volumes of 1M NaOH… - JEE Main 2021 Chemistry PYQ

JEE Main 2021 — Chemistry Physical Chemistry

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The exact volumes of $1M\mathrm{NaOH}$ solution required to neutralise $50\mathrm{mL}$ of $1M{H}_{3}{\mathrm{PO}}_{3}$ solution and $100\mathrm{mL}$ of $2M{H}_{3}{\mathrm{PO}}_{2}$ solution, respectively, are :

Official previous-year question

Held on 16 Mar 2021 · Verified 6 Jul 2026.

Options

A
$100\mathrm{mL}$ and $100\mathrm{mL}$
B
$100\mathrm{mL}$ and $50\mathrm{mL}$
C
$100\mathrm{mL}$ and $200\mathrm{mL}$
D
$50\mathrm{mL}$ and $50\mathrm{mL}$

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Solution

${H}_{3}{\mathrm{PO}}_{3}+2\mathrm{NaOH}\rightarrow {\mathrm{Na}}_{2}{\mathrm{HPO}}_{3}+2{H}_{2}O$

$\begin{matrix}50\mathrm{ml} & 1M\end{matrix}$

$1MV=?$

$\Rightarrow \frac{{n}_{\mathrm{NaoH}}}{{n}_{{H}_{3}{\mathrm{PO}}_{3}}}=\frac{2}{1}$

$\Rightarrow \frac{1\times V}{50\times 1}=\frac{2}{1}\Rightarrow {V}_{\mathrm{NaOH}}=100\mathrm{ml}$

${H}_{3}{\mathrm{PO}}_{2}+\mathrm{NaOH}\rightarrow {\mathrm{NaH}}_{2}{\mathrm{PO}}_{3}+{H}_{2}O$

$2M1M$

$100\mathrm{mL}V=?$

$\Rightarrow \frac{{n}_{\mathrm{NaoH}}}{{n}_{{H}_{3}{\mathrm{PO}}_{3}}}=\frac{1}{1}\Rightarrow \frac{1\times V}{2\times 100}=\frac{1}{1}\Rightarrow {V}_{\mathrm{NaOH}}=200\mathrm{ml}$

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Solution

${H}_{3}{\mathrm{PO}}_{3}+2\mathrm{NaOH}\rightarrow {\mathrm{Na}}_{2}{\mathrm{HPO}}_{3}+2{H}_{2}O$

$\begin{matrix}50\mathrm{ml} & 1M\end{matrix}$

$1MV=?$

$\Rightarrow \frac{{n}_{\mathrm{NaoH}}}{{n}_{{H}_{3}{\mathrm{PO}}_{3}}}=\frac{2}{1}$

$\Rightarrow \frac{1\times V}{50\times 1}=\frac{2}{1}\Rightarrow {V}_{\mathrm{NaOH}}=100\mathrm{ml}$

${H}_{3}{\mathrm{PO}}_{2}+\mathrm{NaOH}\rightarrow {\mathrm{NaH}}_{2}{\mathrm{PO}}_{3}+{H}_{2}O$

$2M1M$

$100\mathrm{mL}V=?$

$\Rightarrow \frac{{n}_{\mathrm{NaoH}}}{{n}_{{H}_{3}{\mathrm{PO}}_{3}}}=\frac{1}{1}\Rightarrow \frac{1\times V}{2\times 100}=\frac{1}{1}\Rightarrow {V}_{\mathrm{NaOH}}=200\mathrm{ml}$

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Options

Did you get this right?

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry