Why is Saturday stronger than Monday?

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

We have shown you a regular water barrel as below. Without using any measuring device can you check if the barrel is more than half-filled or less than half-filled?

John killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

Find the missing number in the image below.

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

In a football game, Christina defeated Teresa by 2 - 0 but no man from either side scored. How can this be possible?

Begin with a word, five letters to my name,
Remove the first and last but I am the same
Take out my middle and still, I remain.
What word am I?

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C

An express train takes 3 seconds to enter the tunnel which is 1 km long.
If it is travelling at 120 km an hour, how long will it take to pass completely through the tunnel?