Question

Convert into passive : "He went to school."

Answer 1

You can't convert this into passive. There is no direct object.

Go is intransitive verb.

Therefore it is not possible.

If you insist, you can change the original sentence to use a transitive verb, say, “He attended school”, and that can be passivized as “School was attended by him” (though it’s very ugly and generally best to avoid).

Answer 2

Gamingnishanth is right.

You can't convert it to passive voice.

It is an incorrect sentence. It has no direct object.

Sorry but it can't be changed to passive voice