Which of the following orders is correct?
(1) `SbH_(3)gt NH_(3) gt AsH_(3) gt PH_(3)-" Boiling Point"`
(2) `NH_(3) gt PH_(3) gt AsH_(3) gt SbH_(3)-" Thermal Stability"`
(3) `NH_(3) gt PH_(3) gt AsH_(3) gt SbH_(3) - "Basic Character"`
(4) `NH_(3) gt PH_(3) gt AsH_(3) gt SbH_(3)- "Bond Angle"`

Options

A. (1), (2) and (3) only
B. (2), (3) and (4) only
C. (1), (3) and (4) only
D. (1), (2), (3) and (4).

Answer

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.