Question

The positive value of the standard electrode potential of Cu2+/Cu indicates
that ____________.
(i) this redox couple is a stronger reducing agent than the H+
/H2 couple.
(ii) this redox couple is a stronger oxidising agent than H+
/H2.
(iii) Cu can displace H2 from acid.
(iv) Cu cannot displace H2 from acid.

Conductivity of an electrolytic solution depends on ____________.
(i) nature of electrolyte.
(ii) concentration of electrolyte.
(iii) power of AC source.
(iv) distance between the electrodes.


NCERT Class XII
Chemistry - Exemplar Problems

Chapter 3. Electrochemistry

Answer 1

The positive value of the standard electrode potential of Cu2+/Cu indicates
that ____________.
(i) this redox couple is a stronger reducing agent than the H+
/H2 couple.
(ii) this redox couple is a stronger oxidising agent than H+
/H2.
(iii) Cu can displace H2 from acid.


(iv) Cu cannot displace H2 from acid.
answer is= (ii) this redox couple is a stronger oxidising agent than H+
/H2.

Conductivity of an electrolytic solution depends on ____________.
(i) nature of electrolyte.
(ii) concentration of electrolyte.
(iii) power of AC source.
(iv) distance between the electrodes.

answer is= (i) nature of electrolyte.

Answer 2

The positive value of the standard electrode potential of $\[C{u^{2 + }}/Cu\]$ indicates that (ii) this redox couple is a stronger oxidising agent than $\[{H^ + }/{H_2}\]$  and (iv) $Cu$ cannot displace $\[{H_2}\]$ from acid. Therefore, both the options (ii) and (iv) are correct.

Explanation:

• The electrode potential can be described as the potential difference between two electrodes.
• The value of electrode potential determines the oxidising and reducing nature of the redox couple.
• If the value of electrode potential is positive, then it is a stronger oxidising agent.
• On the other hand, if the value of electrode potential is negative, then it is a stronger reducing agent.
• The metal having a higher oxidising nature cannot displace the element placed lower than it in the electrochemical series.
• Therefore, the positive value of the standard electrode potential of $\[C{u^{2 + }}/Cu\]$ indicates that this redox couple is a stronger oxidising agent than $\[{H^ + }/{H_2}\]$  and $Cu$ cannot displace $\[{H_2}\]$ from acid.

Conductivity of an electrolytic solution depends on (i) nature of electrolyte and (ii) concentration of electrolyte. Therefore, both the options (i) and (ii) are correct.

Explanation:

• Conductivity is the reciprocal of resistivity.
• It is defined as the conductance of a material of length $\[1\,m\]$ and area of cross-section $\[1\,{m^2}\]$.
• For electrolytic solutions, the conductivity depends on the following factors:

        (i) the nature of the electrolyte

        (ii) the nature of the solvent and its viscosity

        (iii) size of the ions produced and their solvation

        (iv) temperature

        (v) concentration of the electrolyte

• Therefore, among the given options, it depends on the nature of the electrolyte and concentration of electrolyte.

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