What is the riddle which can be asked all day with a different correct answer each time.

Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

I look at you, you look at me, I raise my right, you raise your left. What am I?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

I had an infinite supply of water and 5 litres and 3 litres jars.

How would you measure exactly 4 litres in the least number of steps?

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

A man plots the murder of his wife. His plan is full proof. Nobody saw them leaving their house. He stabbed her with a knife while driving. She died on the spot. He threw her body in a valley. He threw the knife carefully wiping his finger prints on a random garbage bin. Then he went back to his home and no one was watching him this time as well.

After an hour, he was called by the local police department who informed him that his wife was murdered. They asked him to reach the scene of crime immediately. But as soon as he arrived at the crime scene, he was arrested by them.

How did the police know that he himself is the murderer?

Can you replace the question mark with the correct number in the below table sequence?

Find out the missing number in the picture attached:

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?