How many phosphoric acid molecules are found in ADP?

ADP or adenosine di phosphate is an organic compound that is composed of adenosine and two phosphate groups, hence the connotation "di" meaning "two". ADP is the core component of adenosine tri phosphate or ATP. During cell metabolism, when a third phosphate group is added to ADP, the result is formation of ATP which is used for storage of energy on a temporary basis. When the third phosphate group is removed for the purpose of releasing energy, then the molecule becomes ADP again.