Standard reduction electrode potential of four metals A, B, C and D are as follows. The correct order of increasing strength of reducing power is:

A. Metal A = +0.5 V

B. Metal B = -3.0 V

C. Metal C = -1.2 V

D. Metal D = -2.3 V

Choose the correct answer from the options given below:

B > D > C > A

The correct answer is option (1) →  B > D > C > A

• Lower (more negative) Reduction Potential: The metal has a greater tendency to lose electrons (undergo oxidation), making it a stronger reducing agent.
• Higher (more positive) Reduction Potential: The metal has a greater tendency to gain electrons, making it a weaker reducing agent.

Therefore, the reducing power is inversely proportional to the standard reduction potential.

Step-by-Step Analysis

Based on the values given:

1. Metal B: $-3.0\ V$ (Lowest $E^\circ \rightarrow$ Strongest reducing agent)
2. Metal D: $-2.3\ V$
3. Metal C: $-1.2\ V$
4. Metal A: $+0.5\ V$ (Highest $E^\circ \rightarrow$ Weakest reducing agent)

Determining the Order

The question asks for the increasing strength of reducing power (from weakest to strongest):

$A < C < D < B$

However, the options provided use the greater than ($>$) symbol to show the hierarchy from strongest to weakest. Arranging them from the highest reducing power to the lowest:

B > D > C > A

Conclusion

The correct answer is Option 1: B > D > C > A.