Hypophosphorus acid is a monobasic acid as it forms only one type of salts e.g., sodium hydrogen phosphite (NaH2PO2)NaOH+H3PO2NaH2PO2+H2O Hypo phosphorous acid has 2-hydrogen atoms attached to phosphorus and one hydrogen atom attached to oxygen atom (which is ionisable). i.e., H∣H−P−OH∣∣O