Electrochemistry Chemistry - Electrochemistry

1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
3. Assertion is correct statement but reason is wrong statement.
4. Assertion is wrong statement but reason is correct statement.

1. Assertion: For concentration cell, $\text{Zn}_{(\text{s})}|\text{ Zn}^{2+}_{\text{(aq)}}||\text{ Zn}^{2+}_{(\text{aq})}|\text{ Zn}\\\ \ \ \ \ \ \ \ \ \ \ \ \text{C}_1\ \ \ \ \ \ \ \ \text{C}_2$

For spontaneous cell reaction, C₁ < C₂

Reason: For concentration cell, $\text{E}_\text{cell}=\frac{\text{RT}}{\text{nF}}\log\frac{\text{C}_2}{\text{C}_1}$

For spontaneous reaction, $\text{E}_\text{cell}=+\text{ve}\Rightarrow\text{C}_2>\text{C}_1$

2. Assertion: For the cell reaction, $\text{Zn}_{(\text{s})}+\text{Cu}^{2+}_{(\text{aq})}\xrightarrow{\ \ \ \ \ }\text{Zn}^{2+}_{(\text{aq})}+\text{Cu}_{(\text{s})}$ voltmeter gives zero reading at equilibrium.

Reason: At the equilibrium, there is no change in concentration of Cu2+ and Zn2+ ions.

3. Assertion: The Nernst equation gives the concentration dependence of emf of the cell.

Reason: In a cell, current flows from cathode to anode.

4. Assertion: Increase in the concentration of copper half cell in a cell, increases the emfofthe cell.

Reason: $\text{E}_\text{cell}=\text{E}^\circ_\text{cell}+\frac{0.059}{2}\log\frac{[\text{Cu}^{2+}]}{[\text{Zn}^{2+}]}$

5. Assertion: Electrode potential for the electrode $\frac{\text{Mn}^+}{\text{Mn}}$ with concentration is given by the expression under STP conditions.

$\text{E}=\text{E}^\circ+\frac{0.059}{\text{n}}\log[\text{Mn}^{+}]$

Reason: STP conditions require the temperature to be 273K.

1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
3. Assertion is correct statement but reason is wrong statement.
4. Assertion is wrong statement but reason is correct statement.

1. Assertion: The molar conductivity of strong electrolyte decreases with increase in concentration.

Reason: At high concentration, migration ofions is slow.

2. Assertion: The molar conductance of weak electrolyte at infinite dilution is equal to the sum of molar conductance of cations and anions.

Reason: Kohlrausch's law is applicable for strong electrolytes.

3. Assertion: Equivalent conductance of all electrolytes increases with increasing concentration.

Reason: More number ofions are available per gram equivalent at higher concentration.

4. Assertion: Specific conductance decreases with dilution whereas equivalent conductance increases.

Reason: On dilution, number of ions per millilitre decreases but total number ofions increases considerably.

5. Assertion: The ratio of specific conductivity to the observed conductance does not depend upon the concentration of the solution taken in the conductivity cell.

Reason: Specific conductivity decreases with dilution whereas observed conductance increases with dilution.

• It is used to measure relative strengths of various oxidants and reductants.
• It is used to calculate standard cell potential.
• It is used to predict possible reactions.

I₂ + 2e^- → 2I^- ; Eº = 0.54 V

Cl₂ + 2e^- → 2Cl^- ; Eº = 1.36 V

Mn³⁺ +e^- → Mn²⁺ ; Eº = 1.50 V

Fe³⁺ + e^- → Fe²⁺ ; Eº = 0.77 V

O₂ + 4H⁺ + 4e^- → 2H₂O ; Eº = 1.23 V

1. Which of the following statements is correct?

1. Cl^- is oxidised by O₂.
2. Fe²⁺ is oxidised by iodine.
3. I^- is oxidised by chlorine.
4. Mn²⁺ is oxidised by chlorine.

2. Mn³⁺ is not stable in acidic medium, while Fe³⁺ is stable because:

1. O₂ oxidises Mn²⁺ to Mn³⁺
2. O₂ oxidises both Mn²⁺ to Mn³⁺ and Fe²⁺ to Fe³⁺
3. Fe³⁺ oxidises H₂O to O₂
4. Mn³⁺ oxidises H₂O to O₂

3. The strongest reducing agent in the aqueous solution is:

1. I^-
2. Cl^-
3. Mn²⁺
4. Fe²⁺

4. The emf for the following reaction is:

$\text{I}_2+\text{KCl}\rightleftharpoons2\text{KI}+\text{Cl}_2$

1. -0.82 V
2. +0.82 V
3. -0.73 V
4. +0.73 V

5. Which of the following statements is correct for the following reaction?

Fe³⁺ + Mn²⁺ → Fe²⁺ + Mn³⁺

1. The emf of the cell is positive.
2. Fe³⁺ oxidises Mn²⁺.
3. The reaction does not occur.
4. All are correct.

1. At infinite dilution, the equivalent conductance of CaSO₄ is:

1. 256 × 10^-4
2. 279
3. 23.7
4. 2.0 × 10^-8

2. If the degree of dissociation of CaSO₄ solution is 10% then equivalent conductance of CaSO₄ is:

1. 3.59
2. 36.9
3. 27.9
4. 30.6

3. The correct order of equivalent conductance at infinite dilution of LiCl, NaCl, KCl is:

1. LiCl = NaCl = KCl
2. LiCl > NaCl > KCl
3. KCl > LiCl > NaCl
4. KCl > NaCl > LiCl

4. What is the unit of equivalent conductivity?

1. ohm^-1 cm² eq^-1
2. ohm cm² eq-1
3. ohm^-1 cm eq^-1
4. ohm cm^-2eq^-2

5. If the molar conductance value of Ca²⁺ and Cl^- at infinite dilution are 118.88 × 10^-4m² mho mol^-1 and 77.33 × 10^-4m² mho mol^-1 respectively then the molar conductance of CaCl₂ (in m² mho mol^-1) will be:

1. 120.18 × 10^-4
2. 135 × 10^-4
3. 273.54 × 10^-4
4. 192.1 × 10^-4

1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
3. Assertion is correct statement but reason is wrong statement.
4. Assertion is wrong statement but reason is correct statement.

1. Assertion: An electrochemical cell can be set-up only if the redox reaction is spontaneous.

Reason: A reaction is spontaneous if the free energy change is negative.

2. Assertion: The standard electrode potential of hydrogen is 0.0V.

Reason: It is by convention.

3. Assertion: The more negative is the standard reduction potential, greater is its ability to displace H₂ from acid.

Reason: Strength of reducing agent increases with the increase in negative value of the standard reduction potential.

4. Assertion: The negative value of standard reduction potential means that reduction takes place on this electrode with reference to hydrogen electrode.

Reason: The standard electrode potential of a half cell has a fixed value.

5. Assertion: The absolute value of electrode potential cannot be determined experimentally.

Reason: The electrode potential values are generally determined with respect to SHE.