Arrange the following in the decreasing order of reducing power of th…

The correct answer is Option (1) → A, D, B, C

A metal acts as a reducing agent by losing electrons. The standard reduction potential E^o measures the opposite tendency, the tendency of the metal ion to gain electrons. So:

• Lower (more negative) E^o: the metal loses electrons more easily and is a stronger reducing agent.

• Higher (more positive) E^o: the metal holds its electrons and is a weaker reducing agent.

Arranging the potentials from the most negative to the most positive:

    \( \displaystyle -0.44\ (\ce{Fe}) < -0.14\ (\ce{Sn}) < +0.34\ (\ce{Cu}) < +0.80\ (\ce{Ag}) \)

Matching the labels:

• (A) Fe, E^o = −0.44 V: strongest reducing agent

• (D) Sn, E^o = −0.14 V

• (B) Cu, E^o = +0.34 V

• (C) Ag, E^o = +0.80 V: weakest reducing agent

Shortcut: Iron (A) has the most negative potential and silver (C) the most positive, which leaves Options (1) and (3). Tin (−0.14 V) is a stronger reducing agent than copper (+0.34 V), so D comes before B: Option (1).

NCERT (2026-27 edition):
Measurement of Electrode Potential – “… Lithium has the lowest electrode potential indicating that lithium ion is the weakest oxidising agent while lithium metal is the most powerful reducing agent in an aqueous solution. It may be seen that as we go from top to bottom in Table 2.1 the standard electrode potential decreases and with this, decreases the oxidising power of the species on the left and increases the reducing power of the species on the right hand side of the reaction.”