To solve the question regarding the correct orders of boiling point, thermal stability, basic character, and bond angle for the hydrides of group 15 elements (NH₃, PH₃, AsH₃, SbH₃), we will analyze each option step by step.
### Step 1: Analyzing Boiling Points
- **Boiling Point Order**: The order given is `SbH₃ > NH₃ > AsH₃ > PH₃`.
- **Explanation**:
- Antimony (Sb) has the highest molecular weight, thus its hydride SbH₃ has a high boiling point.
- NH₃ has hydrogen bonding due to the presence of a lone pair on nitrogen, which increases its boiling point compared to AsH₃ and PH₃.
- PH₃ and AsH₃ have lower boiling points due to weaker van der Waals forces and no hydrogen bonding.
- **Conclusion**: This order is correct.
### Step 2: Analyzing Thermal Stability
- **Thermal Stability Order**: The order given is `NH₃ > PH₃ > AsH₃ > SbH₃`.
- **Explanation**:
- As we move down the group from nitrogen to antimony, the size of the atom increases, making the M-H bond weaker and thus less thermally stable.
- NH₃ is the most stable due to the strong N-H bond and the presence of hydrogen bonding.
- **Conclusion**: This order is correct.
### Step 3: Analyzing Basic Character
- **Basic Character Order**: The order given is `NH₃ > PH₃ > AsH₃ > SbH₃`.
- **Explanation**:
- Basicity decreases down the group due to increasing atomic size and decreasing electron density around the central atom.
- NH₃ has a small size and a high electron density, making it a strong base, while the larger atoms (P, As, Sb) have lower basicity.
- **Conclusion**: This order is correct.
### Step 4: Analyzing Bond Angles
- **Bond Angle Order**: The order given is `NH₃ > PH₃ > AsH₃ > SbH₃`.
- **Explanation**:
- NH₃ has a bond angle of about 107° due to lone pair-bond pair repulsion.
- As we move down the group, the bond angles decrease because the lone pair-bond pair repulsion decreases as the size of the central atom increases.
- **Conclusion**: This order is correct.
### Final Conclusion
All four statements provided in the question are correct. Therefore, the answer is that all options (1, 2, 3, and 4) are valid.
