Reduction potentials of four elements P, Q, R, S is `-2.90V, 0.34V, 1.2V and -0.76V`. The decreasing order of reducing power is

Options

A. 'P gt Q gt R gt S'
B. S gt R gt Q gt P
C. P gt S gt Q gt R
D. Q gt S gt R gt P

Answer

To determine the decreasing order of reducing power based on the given reduction potentials of elements P, Q, R, and S, we can follow these steps:

### Step 1: Understand the Relationship Between Reduction Potential and Reducing Power
- The reducing power of an element is inversely related to its reduction potential. This means that a higher (more positive) reduction potential indicates a weaker reducing agent, while a lower (more negative) reduction potential indicates a stronger reducing agent.

### Step 2: List the Given Reduction Potentials
- The reduction potentials for the elements are:
- P: -2.90 V
- Q: 0.34 V
- R: 1.2 V
- S: -0.76 V

### Step 3: Arrange the Reduction Potentials in Increasing Order
- To find the decreasing order of reducing power, we first arrange the reduction potentials from the lowest to the highest:
1. P: -2.90 V
2. S: -0.76 V
3. Q: 0.34 V
4. R: 1.2 V

### Step 4: Determine the Corresponding Reducing Power
- Since reducing power is inversely related to reduction potential, the order of reducing power (from strongest to weakest) will be the reverse of the order of reduction potentials:
- Strongest reducing power: P (most negative potential)
- Next: S
- Then: Q
- Weakest reducing power: R (most positive potential)

### Step 5: Write the Final Order of Reducing Power
- Therefore, the decreasing order of reducing power is:
- P > S > Q > R

### Final Answer
The decreasing order of reducing power is: **P > S > Q > R**