H3PO3 is the chemical formula for phosphorous acid. However, phosphorous acid does not actually exist as H3PO3 in a stable form. The correct formula for phosphorous acid is H3PO3, which contains only two hydrogen atoms.
In phosphorous acid (H3PO3), the central phosphorus atom is bonded to three hydrogen atoms and one hydroxyl group (-OH). The hydroxyl group can dissociate to release a hydrogen ion (H+) and form a phosphate ion (H2PO3-), resulting in the loss of one hydrogen atom. Therefore, phosphorous acid can lose only one hydrogen atom, not two.
It's important to note that there might be a misunderstanding or misinformation regarding the number of hydrogen atoms in phosphorous acid in your question. The correct formula and behavior of phosphorous acid as described above should be considered.