Solution:

O + Pi + nion (Pi In Onion)
= Opinion

Solution:

A Mirror

Solution:

It can be done as shown in the picture below.

Solution:

All men lose the upper body and getting less for exchange. In this way, the losses of parts, account for one vanished one.

Watch the video for more detail.

Solution:

10 + 10 = 20
11 + 11 = 22 or we can say 20 too.

Solution:

The third Man as there is no shadow of the man.

Solution:

1. The word "are" is repeated twice.
2. The word "to" is repeated twice.
3. The word mitstakes is misspelled. Its should be mistakes
4. The sentence is missing a punctuation mark and should end with a period/full stop not with semicolon.
5. Since there are only 4 mistakes, therefore, the statement of having five mistakes in the sentence is wrong which is the 5th mistake.

Solution:

All are at an equal distance from the ceiling.

Solution:

123 - 45 - 67 + 89

Solution:

25