What is at the end of a rainbow?

Below the four parts have been reorganised. The four partitions are exactly the same in both arrangements. Why is there a hole?

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

Can you tell a 3D object that has just two surfaces?

You have two buckets - one holds exactly 5 gallons and the other 3 gallons. How can you measure 4 gallons of water into the 5 gallon bucket?

(Assume you have an unlimited supply of water and that there are no measurement markings of any kind on the buckets.)

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

Steffi's daughter Jazelle needs to be picked up from school every day.
Steffi asks one of her colleagues to pick up Jazelle from the school. Steffi devised a password system to confirm that Jazelle goes with the correct colleague only.

The password on Monday was SJM16.
The password on Wednesday was TAW39.

What will the password be for Friday?

I’m tall when I’m young, and I’m short when I’m old. What am I?

I am a number I am not an odd number I am higher than 90 I am not higher than 100 If you subtract me from 100, you get nothing. What number am I?

A bomb exploded in a room full of married couples and no one died. How?