The incorrect statement regarding 15th group hyrides `(EH_(3)).[E=N,P,As,Sb,Bi]`

Options

A. `NH_(3) gt PH_(3) gt AsH_(3)gtSbH_(3) gt BiH_(3)`:Thermal stability
B. `N-H gt P-H gt As-H gt Sb-H gt Bi-H,E-H` bond dissociation enthalpy
C. `NH_(3) gt PH_(3) gt AsH_(3) gt SbH_(3) gt BiH_(3):` Reducing character
D. `NH_(3) gt PH_(3) gt AsH_(3) gt SbH_(3) gt BiH_(3)`: Basicity

Explanation

To determine the incorrect statement regarding the hydrides of the 15th group elements (E = N, P, As, Sb, Bi), we will analyze the properties and trends of these hydrides step by step.

### Step 1: Identify the Group 15 Elements
The elements in Group 15 are:
- Nitrogen (N)
- Phosphorus (P)
- Arsenic (As)
- Antimony (Sb)
- Bismuth (Bi)

### Step 2: Analyze the Hydrides
The hydrides of these elements are:
- NH₃ (Ammonia)
- PH₃ (Phosphine)
- AsH₃ (Arsine)
- SbH₃ (Stibine)
- BiH₃ (Bismuthine)

### Step 3: Examine Thermal Stability
As we move down the group from nitrogen to bismuth, the size of the central atom increases, which affects the bond strength with hydrogen. The bond dissociation energy decreases due to the larger atomic size, leading to lower thermal stability. Thus, the order of thermal stability is:
- NH₃ > PH₃ > AsH₃ > SbH₃ > BiH₃

### Step 4: Evaluate Bond Dissociation Energy
The bond dissociation energy is highest for NH₃ and decreases down the group. This means that NH₃ has the strongest bond and requires more energy to break compared to the other hydrides.

### Step 5: Assess Reducing Character
The reducing character of these hydrides is inversely related to their bond dissociation energy. A stronger bond (like in NH₃) means it is less likely to donate hydrogen, making it a weaker reducing agent. Therefore, the order of reducing character should be:
- BiH₃ > SbH₃ > AsH₃ > PH₃ > NH₃

### Step 6: Check Basicity
The basicity of these hydrides also follows a trend where NH₃ is the most basic due to the availability of its lone pair, while the basicity decreases down the group due to the increasing size of the central atom, which makes the lone pair less available for donation.

### Conclusion
Based on the analysis, the incorrect statement regarding the hydrides of the 15th group is related to the reducing character. The statement claiming NH₃ has the highest reducing character is incorrect. The correct order of reducing character is inversely proportional to bond dissociation energy, leading to BiH₃ being the strongest reducing agent.

### Summary of Incorrect Statement
The incorrect statement is that NH₃ has the highest reducing character. The correct order is:
- BiH₃ > SbH₃ > AsH₃ > PH₃ > NH₃