Answer: The chemical formula for phosphorous acid is
![H_3PO_3](https://img.qammunity.org/2020/formulas/chemistry/college/humqib8k019u7w05g68xmyko8gcqsa72mr.png)
Step-by-step explanation:
An acid is defined as the substance which releases hydrogen ions on dissolving in water.
Phosphorous acid is an acid which is formed by the combination of hydrogen ions
and phosphite ion having formula
![PO_3^(3-)](https://img.qammunity.org/2020/formulas/chemistry/middle-school/k2z0d0r7d6zb60nkgu8imx7yest0j8heel.png)
By criss-cross method, the oxidation state of the ions gets exchanged and they form the subscripts of the other ions. This results in the formation of a neutral compound.
Hence, the chemical formula for phosphorous acid is
![H_3PO_3](https://img.qammunity.org/2020/formulas/chemistry/college/humqib8k019u7w05g68xmyko8gcqsa72mr.png)