Decide in which of the following sentences you can use if

Decide in which of the following sentences you can use if instead of whether.
1) May I ask you whether you like classical music?
2) They were not certain of whether the task would be too hard for them.
3) Do you know whether this story has a happy ending?
4) The girl is still thinking whether to marry him.
5)Whether the day is warm or not, we are planning to spend it outdoors.
6) Ask your friend whether he will be able to join us for supper.
7) I still don't know whether or not he us planning to come.
8) We are in two minds about whether or not we should take he invitation.
9)Mark asks whether we are ready to begin the discussion
10)The problem is whether or not we have visitors from abroad.