When a phosphate bond is hydrolyzed, energy is released. the remaining adp is at a higher or lower energy state?

The remaining ADP is at lower energy state.

Explanation:

ATP contain three phisphate bond. These phosphate groups form phosphodiester bond. Hydrolysis of each phosphate bond release about 7.3 Kcal of energy and one ADP. Now this ADP contain only one bond between phosphate group.

Result:

It is clered from the discussion that ADP is at lower energy level as compared to ATP due to less bond between phosphate group.