Can someone please very simply explain the oxymoron for 3,4,6 and 7

Answer:
The selected oxymoron and its meanings are given for your reference.
Explanation:
Lead balloon - Fail Completely and be considered flop by public.
Minor Miracle - something good that is not very likely to happen but does happen
Unbiased Opinion - An opinion is an expression of personal belief, so it cannot be unbiased.
Friendly Takeover - Acquisition of one firm by another where the owners of both firms agree to the terms of the takeover transaction.