Both slicing a tomato and a chemical change such as burning toast cannot be reversed however why is slicing a tomato still considered only a physical change

Both slicing a tomato and a chemical change such as burning toast cannot be reversed. Slicing a tomato still considered only a physical change because you are only altering the shape of the tomato by slicing. It does not change in color or produce bubbles when slicing.

the answer is na (sodium)