The correct order of reducing abilities of VA group hydrides is 

Options

A. `NH_(3) lt PH_(3) lt AsH_(3) lt SbH_(4) lt BiH_(3)`
B. `NH_(3)gt PH_(3) gt AsH_(3) gt SbH_(4) gt BiH_(3)`
C. `NH_(3) lt PH_(3) gt AsH_(3) gt SbH_(3) gt BiH_(3)`
D. `SbH_(3) gt BiH_(3) gt AsH_(3) gt NH_(3) gt PH_(3)`.

Answer

To determine the correct order of reducing abilities of VA group hydrides (NH3, PH3, AsH3, SbH4, and BiH4), we can follow these steps:

### Step 1: Understand the Relationship Between Stability and Reducing Ability
- The reducing ability of a hydride is inversely related to its stability. This means that the less stable a hydride is, the stronger its reducing ability.

### Step 2: Determine the Stability Order of VA Group Hydrides
- The stability of the hydrides in Group VA can be arranged as follows:
- NH3 (Ammonia) > PH3 (Phosphine) > AsH3 (Arsine) > SbH4 (Stibine) > BiH4 (Bismuthine)
- This order indicates that ammonia is the most stable, while bismuthine is the least stable.

### Step 3: Infer the Reducing Ability Order
- Since reducing ability is inversely proportional to stability, we can deduce the order of reducing abilities:
- BiH4 (most reducing) > SbH4 > AsH3 > PH3 > NH3 (least reducing)
- Thus, the order of reducing abilities is:
- BiH4 > SbH4 > AsH3 > PH3 > NH3

### Conclusion
- The correct order of reducing abilities of VA group hydrides is:
- **BiH4 > SbH4 > AsH3 > PH3 > NH3**