Final answer:
The chemical formula for phosphorous trihydride is PH₃, also known as phosphine. It is a colorless, flammable, and toxic gas that is generated through chemical reactions but not by direct combination of phosphorus and hydrogen.
Step-by-step explanation:
The chemical formula for phosphorous trihydride is PH₃. This compound is commonly known as phosphine. Phosphine is a colorless, flammable, and toxic gas with an odor like that of decaying fish. It is not produced by the direct union of its elements, but through reactions such as the action of an acid on an ionic phosphide or the disproportionation of white phosphorus with hot concentrated base.
Among the answer choices provided for the chemical formula of phosphorous trihydride:
- Phosphorus hexahydride is not the correct answer. There is no phosphorus compound with six hydrogen atoms officially recognized.
- Phosphorus hydride is an incomplete name that does not specify the number of hydrogen atoms.
- Phosphorus trioxide is incorrect and refers to a different compound, P₄O₆.
- Phosphorus trichloride is also incorrect as it refers to PCl₃, which contains chlorine instead of hydrogen.