Question

He has cooked food.(change in passive voice)​

Answer 1

He has cooked food.

(In passive voice)

=>Food has been cooked by her.

{As the "food" is object and "he" is subject so both their places will be exchanged as well as 3rd form of verb will use and "been" is also used.}

Answer 2

Here is your answer ⤵⤵⤵

☣Food has been cooked by her.

Thanks ☺