What does the below image rebus riddle means ?

How can you tell a raw egg from a hard-boiled egg?

Can you convert the number zero(0) into a positive number using just one mathematical operator ?

You can see it everyday, But cannot touch it at will. What is it?

I am a word that begins with the letter “i.” If you add the letter “a” to me, I become a new word with a different meaning, but that sounds exactly the same. What word am I?

What seven-letter word has hundreds of letters in it?

If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left?

You find yourself in a strange place guarded by two guards.One of the guard always say truth while other always lies.You don't know the identity of the two.You can ask only one question to go out from there. What should you ask?

The host of a game show, offers the guest a choice of three doors. Behind one is a expensive car, but behind the other two are goats.
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).

Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.

You cannot hear the goats from behind the doors, or in any way know which door has the prize.

Should you stay, or switch, or doesn't it matter?

What Time Should the last watch show in the below figure?