Decreasing order of reducing power of the given species as per their standard reduction potential is :
A. −2.36
B. +0.54
C. +1.23
D. −0.74
E. +1.81
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → A > D > B > C > E
The lower (more negative) the standard reduction potential, the less the species tends to be reduced, and the more readily its reduced form gives up electrons. So reducing power increases as E° decreases. Placing each species, strongest reducing agent first:
A. −2.36 V — first. The most negative potential.
D. −0.74 V — second.
B. +0.54 V — third. The first positive value.
C. +1.23 V — fourth.
E. +1.81 V — last. The highest potential, so the weakest reducing agent (its oxidised form is the strongest oxidising agent).
NCERT (2026-27 edition):
Measurement of Electrode Potential – “… 1. A negative Eo means that the redox couple is a stronger reducing agent than the H+/H2 couple. A positive Eo means that the redox couple is a weaker reducing agent than the H+/H2 couple.”