JEE Main 2026 — Chemistry Physical Chemistry

2026mcqmedium

One half cell in a voltaic cell is constructed by dipping silver rod in $AgNO_3$ solution of unknown concentration, other half cell is $Zn$ rod dipped in $1$ molar solution of $ZnSO_4$ . A voltage of $1.60\text{ V}$ is measured at $298\text{ K}$ for this cell. What is the concentration of $Ag^+$ ions used in terms of $\log x$ ( $x = [Ag^+]$ ) ?

$E^\circ_{Zn^{2+}/Zn} = -0.76\text{ V}$ , $E^\circ_{Ag^+/Ag} = +0.80\text{ V}$ , $\dfrac{2.303 RT}{F} = 0.059\text{ V}$

Official previous-year question

Held on 5 Apr 2026 · Verified 6 Jul 2026.

Options

A
$\dfrac{2}{3.9}$
B
$\dfrac{4}{5.9}$
C
$\dfrac{2.9}{2}$
D
$\dfrac{5.9}{4}$

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Solution

The cell reaction is $Zn(s) + 2Ag^+(aq) \rightarrow Zn^{2+}(aq) + 2Ag(s)$

The standard cell potential is given by:

$E^\circ_{cell} = E^\circ_{cathode} - E^\circ_{anode} = 0.80 - (-0.76) = 1.56\text{ V}$

Using the Nernst equation:

$E_{cell} = E^\circ_{cell} - \dfrac{0.059}{n} \log \dfrac{[Zn^{2+}]}{[Ag^+]^2}$

Substituting the given values ( $n = 2$ , $[Zn^{2+}] = 1\text{ M}$ , $E_{cell} = 1.60\text{ V}$ ):

$1.60 = 1.56 - \dfrac{0.059}{2} \log \dfrac{1}{x^2}$

$0.04 = - \dfrac{0.059}{2} (-2 \log x)$

$0.04 = 0.059 \log x$

$\log x = \dfrac{0.04}{0.059} = \dfrac{4}{5.9}$

Answer: $\dfrac{4}{5.9}$

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Solution

The cell reaction is $Zn(s) + 2Ag^+(aq) \rightarrow Zn^{2+}(aq) + 2Ag(s)$

The standard cell potential is given by:

$E^\circ_{cell} = E^\circ_{cathode} - E^\circ_{anode} = 0.80 - (-0.76) = 1.56\text{ V}$

Using the Nernst equation:

$E_{cell} = E^\circ_{cell} - \dfrac{0.059}{n} \log \dfrac{[Zn^{2+}]}{[Ag^+]^2}$

Substituting the given values ( $n = 2$ , $[Zn^{2+}] = 1\text{ M}$ , $E_{cell} = 1.60\text{ V}$ ):

$1.60 = 1.56 - \dfrac{0.059}{2} \log \dfrac{1}{x^2}$

$0.04 = - \dfrac{0.059}{2} (-2 \log x)$

$0.04 = 0.059 \log x$

$\log x = \dfrac{0.04}{0.059} = \dfrac{4}{5.9}$

Answer: $\dfrac{4}{5.9}$

JEE Main 2026 — Chemistry Physical Chemistry

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Solution

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JEE Main Physical Chemistry in other years

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JEE Main 2026 — Chemistry Physical Chemistry

Options

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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

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