Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.

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?

How far can you walk into the woods?

You are in a room that has three switches and a closed door. The switches control three light bulbs on the other side of the door. Once you open the door, you may never touch the switches again. How can you definitively tell which switch is connected to each of the light bulbs?

What do you think with the below Picture ?

My first is in chocolate but not in ham. My second is in cake and also in jam. My third at tea time is easily found. Altogether, this is a friend who is often around. What is it?

You can hear me, but you can't touch or see me.

What am I?

Count the Triangle in the figure given below:

In a boat, the father of a sailor's son is sitting with the son of the sailor. However, the sailor is not present on the boat.

Can this even be possible?

How many cubic feet of dirt are in a hole of one foot deep, three feet long, and two feet wide?