Concept:Basicity is the number of replaceable hydrogen ions (
H+) that one molecule of an acid can donate during a neutralisation reaction.
Explanation:Tetraoxophosphate(V) acid is the IUPAC name for phosphoric acid, with the molecular formula
H3PO4.
Its structure contains three hydrogen atoms bonded to oxygen atoms as
O−H groups.
In aqueous solution, each of these three hydrogen atoms can be released as
H+ ions.
Therefore, one molecule of
H3PO4 can produce up to three hydrogen ions.
Since the acid can donate three protons, its basicity is equal to
3.
This classifies
H3PO4 as a tribasic acid.
Answer:The basicity of tetraoxophosphate(V) acid is
3, so the correct option is D.