Solution:

BACK

All the others can also be read backwards as proper words.

Solution:

They all read the same rightside or upside down.

Solution:

61

Reversed digits of squares of number in descending order.

Solution:

When he took the first bite of the salmon, he realized that what he ate at the island was not salmon but his friend

Solution:

$16

Solution:

There are sixty marks in the given figure, thus it is safe to assume that each mark represents a minute.

Now, the hour hand is on a mark when the minute hand is on [0, 12, 24, 36, 48]. When the minute hand is on a mark, the second hand is on noon. But the orange hand cannot be the second hand. (It would be onnoon and it would be eighteen minutes past/before a full hour.)

a) Purple is on 12. Green indicates twenty four minutes. orange indicates forty two [minutes] = 8 + 2/5 [hours] = 8:24
b) Purple is on 12. Green indicates thirty six minutes. orange indicates eighteen [minutes] = 3 + 3/5 [hours] = 3:36
c) Green is on 12 = 3:36
d) Green is on 12 = 8:24.

Please note that the watch could be rotated upside down as well.

Solution:

They can neither be true nor be false. They contradict each other and these statements are known as paradox.

Solution:

The third son bought a candle and a matchstick. He lighted the candle from the matchstick and the light filled the entire room.

Solution:

18

Solution:

One in a million