In the given condition where the thylakoids are isolated from the chloroplasts to make the pH of the thylakoid space acidic, the isolated thylakoid will form the ATP.
ATP is also referred to as Adenosine Triphosphate and is correctly called as the energy currency of the cell as it is responsible molecule for carrying the energy units in the cell. When the isolated thylakoids are made to transfer in the pH = 8 basic solution, then the acidic lumen of the chloroplast will be having a higher concentration of H⁺ ions. When they are placed in the basic solution then the H⁺ ions will move out because of the occurrence of concentration gradient which is higher in the lumen than the surrounding. The chloroplasts will now bear synthesis of ATP. Therefore, the isolated thylakoid is able to make ATP when the lumen is acidic, and the surroundings are made basic in nature.
Thus, the thylakoid which is isolated will bear the synthesis of ATP.