If you say my name, I will no longer exist. What am I?

Evil warlock dislikes dwarfs and therefore he selects four of them and buries them. The dwarfs are buried in the ground and they are in such a way that except for their heads, their body is inside the ground. The dwarfs cannot move their body and they can view only forward. They are all buried in a line, and amongst the four, one of the dwarfs is separated by a wall. All the dwarfs are in the same direction. The last dwarfs can see two heads of friends in the front and a wall. In the last second dwarf can see one head of his friend and a wall. The second dwarf can see only the wall. The dwarf can see nothing.
Warlock comprehends the situation and tells the dwarfs that he has placed hats on their heads. There are two blue hats and two red ones. In all four dwarfs, one of them has to say what colour hat he is wearing. If the dwarf says the correct colour of the hat, they will be left free. If the answer is wrong, then they will be dug inside the ground till the very end.

What will be the answer by the dwarf and how will they answer?

John was visiting his friend Jacob. He found out that his friend's wife had just killed a burglar in self-defense.
John asks Jacob about what happened and he told that "His wife was watching television when suddenly the bell rang. She thought that it is her husband Jacob but she found the burglar who attacked her instantly and she got so frightened that she killed the burglar immediately with the knife.
John asked the police to arrest his friend's wife. Why?

A man is found unconscious in front of a store at two in the morning. His head is bleeding and there’s a brick laying next to him. When the police arrive, they carry the man to jail. Why did they arrest him?

Why is 6 afraid of 7?

The two towns are exactly 100 km apart. John leaves City A driving at 30 km/hr and Jacob leaves City B half an hour later driving at 60 km/hr. Who will be closer to City A when they meet?

What can you see in the middle of March and April that you can never see in any other month?

Replace the question mark with the correct number in the below-given picture?

Replace the question mark with the correct number, given the pair of numbers exhibits a similar relationship?

? : 3839 :: 11 : 1209

You are a thief and you are being punished for your crime. People have tied your head down on a tree with a rope that has been anchored in the ground. A candle is burning below the rope which is slowly burning it away. Just below your head, a Lion has been left loose and is waiting for you to drop down on the ground so he can have you as his lunch.

You have to survive the scenario. How will you do it?