Question

Which of the following will act as cathode when connected to standard hydrogen electrode which has $E^{\circ }$ value given as zero?
$\left(i\right)Z{n}^{2+}/Zn$, $E^{\circ }=-0.76V$
$\left(ii\right)C{u}^{2+}/Cu$, $E^{\circ }=+0.34V$
$\left(iii\right)A{l}^{3+}/Al$, $E^{\circ }=-1.66V$
$\left(iv\right)H{g}^{2+}/Hg$, $E^{\circ }=+0.885V$

• A. (i) and (ii)
• B. (ii) and (iv)
• C. (i) and (iii)
• D. (i), (ii), (iii) and (iv)

Answer 1

Answer: (B)

When the value of standard reduction potential is positive, the electrode undergoes reduction and acts as cathode.