What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

In the picture given below, can you find out which digit will take place of the question mark?

If two's company, and three's a crowd, then whats four and five ?

What time is it when an elephant sits on a fence?

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

From a pack of 52 cards, I placed 4 cards on the table.

I will give you 4 clues about the cards:

Clue 1: Card on left cannot be greater than the card on the right.
Clue 2: Difference between the 1st card and 3rd card is 8.
Clue 3: There is no card of an ace.
Clue 4: There are no face cards (queen, king, jacks).
Clue 5: Difference between the 2nd card and 4th card is 7.

Identify four cards?

What begins with T, ends with T, and has T in it?

You walk into a creepy house by yourself. There is no electricity, plumbing, or ventilation. Inside you notice 3 doors with numbers on them. Once you open the doors you will die a particular way. Door No.1 You’ll be eaten by a lion who is hungry. Door No.2 You’ll be stabbed to death. Door No.3 There is an electric chair waiting for you. Which door do you pick?

Get total of 120 by using five zeros 0,0,0,0,0 and any one mathematical operator.
Do you ?

I have nine bottles of wine and one of the nine bottles is poisoned.
I need to find the poisoned bottle with two facts
(1) Poison is deadly, only a sip will cost death
(2) I have two mice to do so.

How should I do it?