# Two half cell reactions are given below: \begin{aligned} &\mathrm{Co}^{3+}+e^{-} \rightarrow \mathrm{Co}^{2+}, \mathrm{E}_{\mathrm{Co}^{2+} / \mathrm{Co}^{3+}}^{\circ}=-1.81 \mathrm{~V} \\ &2 \mathrm{Al}^{3+}+6 e^{-} \rightarrow 2 \mathrm{Al}(\mathrm{s}), \mathrm{E}_{\mathrm{Al} / \mathrm{Al}^{3+}}^{\circ}=+1.66 \mathrm{~V} \end{aligned} The standard EMF of a cell with feasible redox reaction will be: 1. +7.09 V 2. +0.15 V 3. +3.47 V 4. –3.47 V

Subtopic:  Electrode & Electrode Potential |
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Standard electrode potential for the cell with cell reaction
Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s)
is 1.1 V. Calculate the standard Gibbs energy change for the cell reaction.
(Given F = 96487 C mol–1)
 1 –200.27 kJ mol–1 2 –212.27 kJ mol–1 3 –212.27 J mol–1 4 –200.27 J mol–1
Subtopic:  Relation between Emf, G, Kc & pH |
80%
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NEET - 2022
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$$\land^o_m$$ for NaCl, HCl and $$\mathrm{CH_3COONa }$$ are 126.4, 425.9, and 91.05 S cm2 mol–1 respectively. If the conductivity of 0.001028 mol L–1 acetic acid solution is $$4.95 \times 10^{-5} S ~cm^{-1}$$, the degree of dissociation of the acetic acid solution is:

 1 0.01233 2 1 3 0.1233 4 1.233
Subtopic:  Conductance & Conductivity |
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The three cells with their $$E^\circ_{\text{(cell)}}$$ values are given below:

 Cells $$E^\circ_{\text{(cell)}}/V$$ (a) Fe|Fe2+||Fe3+|Fe 0.404 (b) Fe|Fe2+||Fe3+, Fe2+|Pt 1.211 (c) Fe|Fe3+||Fe3+, Fe2+|Pt 0.807
The standard Gibbs free energy change values for three cells are, respectively:
(F represents the charge on 1 mole of electrons.)

 1 –1.212 F, –1.211 F, –0.807 F 2 +2.424 F, +2.422 F, +2.421 F 3 –0.808 F, –2.422 F, –2.421 F 4 –2.424 F, –2.422 F, –2.421 F
Subtopic:  Faraday’s Law of Electrolysis |
56%
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NEET - 2022
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Find the emf of the cell in which the following reaction takes place at 298 K:
$$\mathrm{Ni}(\mathrm{s})+2 \mathrm{Ag}^{+}(0.001 \mathrm{M}) \rightarrow \mathrm{Ni}^{2+}(0.001 \mathrm{M})+2 \mathrm{Ag}(\mathrm{s})$$
$$\small{\text { (Given that } \mathrm{E}_{\text {cell }}^{\circ}=10.5 \mathrm{~V}, \frac{2.303 \mathrm{RT}}{\mathrm{F}}=0.059 \text { at } \ 298 \mathrm{~K})}$$
1. 1.05 V
2. 1.0385 V
3. 1.385 V
4. 0.9615 V

Subtopic:  Nernst Equation |
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Given below are half-cell reactions:
$$\mathrm{MnO}_{4}^{-}+8 \mathrm{H}^{+}+5 \mathrm{e}^{-} \rightarrow \mathrm{Mn}^{2+}+4 \mathrm{H}_{2} \mathrm{O},$$
$$\mathrm{E}_{\mathrm{Mn}^{2+}}^{\circ} / \mathrm{MnO}_{4}^{-}=-1.510 \mathrm{~V}$$
$$\frac{1}{2} \mathrm{O}_{2}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \rightarrow \mathrm{H}_{2} \mathrm{O},$$
$$\mathrm{E}_{\mathrm{O}_{2} / \mathrm{H}_{2} \mathrm{O}}^{\circ}=+1.223 \mathrm{~V}$$
Will the permanganate ion, $$\mathrm{MnO}_{4}^{-}$$ , liberate $$\mathrm{O}_{2}$$ from water in the presence of an acid?

1. No, because $$\mathrm{E}_{\text {cell }}^{\circ}=-2.733 \mathrm{~V}$$
2. Yes, because $$\mathrm{E}_{\text {cell }}^{\circ}=+0.287 \mathrm{~V}$$
3. No, because $$\mathrm{E}_{\text {cell }}^{\circ}=-0.287 \mathrm{~V}$$
4. Yes, because $$\mathrm{E}_{\text {cell }}^{\circ}=+2.733 \mathrm{~V}$$
Subtopic:  Electrode & Electrode Potential |
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Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R):
 Assertion (A): In equation $$\Delta_{\mathrm{r}} \mathrm{G}=-\mathrm{nFE} _{\text {cell }},$$ value $$\mathrm{\Delta_rG }$$ depends on n. Reason (R): $$\mathrm{E_{cell} }$$ is an intensive property and  $$\mathrm{\Delta_rG }$$  is an extensive property.

In the light of the above statements choose the correct answer from the options given below:

 1 (A) is False but (R) is True. 2 Both (A) and (R) are True and (R) is the correct explanation of (A). 3 Both (A) and (R) are True and (R) is not the correct explanation of (A). 4 (A) is True but (R) is False.
Subtopic:  Relation between Emf, G, Kc & pH |
57%
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NEET - 2023
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The conductivity of centimolar solution of KCl at 25°C is 0.0210 ohm–1 cm–1 and the resistance of the cell containing the solution at 25°C is 60 ohm. The value of the cell constant is:
 1 3.34 cm–1 2 1.34 cm–1 3 3.28 cm–1 4 1.26 cm–1
Subtopic:  Conductance & Conductivity |
77%
From NCERT
NEET - 2023
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The molar conductance of an electrolyte increases with dilution according to the equation:
$$\Lambda_{\mathrm{m}}=\Lambda_{\mathrm{m}}^{\circ}-\mathrm{A} \sqrt{\mathrm{c}}$$
Consider the following four statements:
 A: This equation applies to both strong and weak electrolytes. B: The value of the constant A depends upon the nature of the solvent. C: The value of constant A is the same for both $$BaCl_2$$ and $$MgSO_4$$ D: The value of constant A is the same for both $$BaCl_2$$ and $$Mg(OH)_2$$
Which of the above statements are correct?
1. (A) and (B) only
2. (A), (B), and (C) only
3. (B) and (C) only
4. (B) and (D) only
Subtopic:  Conductance & Conductivity |
55%
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NEET - 2023
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The correct value of cell potential in volt for the reaction that occurs when the following two half cells are connected, is:
$$\mathrm{Fe}_{\text {(aq) }}^{2+}+2 \mathrm{e}^{-} \rightarrow \mathrm{Fe}(\mathrm{s}), \mathrm{E}^{\circ}=-0.44 \mathrm{~V}$$
$$\mathrm{Cr}_2 \mathrm{O}_7^{2-}{ }_{\text {(aq) }}+14 \mathrm{H}^{+}+6 e^{-} \rightarrow 2 \mathrm{Cr}^{3+}+7 \mathrm{H}_2 \mathrm{O},$$
$$\mathrm{E}^{\circ}=+1.33 \mathrm{~V}$$
 1 +1.77 V 2 +2.65 V 3 +0.01 V 4 +0.89 V
Subtopic:  Electrode & Electrode Potential |
72%
From NCERT
NEET - 2023