Question

Who has broken this glass? Change to passive voice

Answer 1

hey mate ur and is

THIS GLASS IS BROKEN BY WHOM

MAY THIS HELPS YOU

GOOD TO HELP YOU

TY .. HAVE A NYC DAY

Answer 2

This glass has been broken by whom?

you just have to make the subject(who) the object and the object(this glass) the subject.
You also have to make a little corrections to make the sentence gramatically correct like

WHO becomes WHOM
also add by