- 
					 An acid having basicity one is
- 
                        -  Sodium dihydrogen phosphate 
 
-  Disodium hydrogen phosphate 
 
-  Sodium phosphate 
 
- Phosphoric acid
 
-  Sodium dihydrogen phosphate 
Correct Option: B
The basicity of an acid is the number of hydrogen ions (H+) which can be produced by the ionization of one molecule of the acid in aqueous solution. For example, the basicity of hydrochloric acid is 1 since one molecule of HCl produces one H+ ion in solution. Similarly, the basicity of Disodium phosphate (Na2HPO4) is one since it has one H+ displaceable ion.
 
	