I. Boiling point order: SbH3 > NH3 > AsH3 > PH3

The boiling point of a compound is determined by the strength of intermolecular forces. In this case, we are comparing the boiling points of hydrides of elements in Group 15 of the periodic table (Nitrogen, Phosphorus, Arsenic, and Antimony).

- Antimony hydride (SbH3) has the highest boiling point among the given compounds because it has the strongest intermolecular forces. This can be attributed to the presence of a larger atom with more electrons, resulting in stronger London dispersion forces.
- Ammonia (NH3) has a lower boiling point compared to SbH3 because nitrogen is smaller and has fewer electrons, leading to weaker intermolecular forces.
- Arsenic hydride (AsH3) has a lower boiling point than NH3 because arsenic is larger than nitrogen, resulting in weaker intermolecular forces.
- Phosphine (PH3) has the lowest boiling point among the compounds because phosphorus is the smallest and has the fewest electrons, leading to the weakest intermolecular forces.

Therefore, the correct order of boiling points is SbH3 > NH3 > AsH3 > PH3.

II. Thermal stability order: NH3 > PH3 > AsH3 > SbH3

Thermal stability refers to the ability of a compound to withstand decomposition at high temperatures. In this case, we are comparing the thermal stability of the hydrides.

- Ammonia (NH3) is the most thermally stable among the given compounds. It has strong N-H bonds, which are difficult to break, and it does not decompose easily at high temperatures.
- Phosphine (PH3) is less thermally stable compared to NH3 because P-H bonds are weaker than N-H bonds and can break more easily at high temperatures.
- Arsenic hydride (AsH3) is less thermally stable than PH3 because As-H bonds are weaker than P-H bonds.
- Antimony hydride (SbH3) is the least thermally stable among the compounds because Sb-H bonds are weaker than As-H bonds.

Therefore, the correct order of thermal stability is NH3 > PH3 > AsH3 > SbH3.

III. Basic character order: NH3 > PH3 > AsH3 > SbH3

The basic character of a compound is determined by its ability to donate a lone pair of electrons. In this case, we are comparing the basicity of the hydrides.

- Ammonia (NH3) is the most basic among the given compounds. Nitrogen has a lone pair of electrons that it can donate to form a coordinate bond with an acid.
- Phosphine (PH3) is less basic compared to NH3 because phosphorus is less electronegative than nitrogen, resulting in a weaker electron-donating ability.
- Arsenic hydride (AsH3) is less basic than PH3 because arsenic is less electronegative than phosphorus.
- Antimony hydride (SbH3) is the least basic among the compounds because antimony is less electronegative than arsenic.

Therefore, the correct order of basic character is NH3 > PH3 > AsH3 >