Can you find the odd number in the following?

2716, 4135, 5321 and 7145

If an electric train is travelling south, then which way is the smoke going?

You can see it everyday, But cannot touch it at will. What is it?

In which direction should the missing arrow point?

Move three sticks of the spiral below to form a square.

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

You are driving down the road in your car on a wild, stormy night, when you pass by a bus stop and you see three people waiting for the bus

An old lady looks as if she is about to die.
An old friend who once saved your life.
The perfect partner you have been dreaming about.
Knowing that there can only be one passenger in your car, whom would you choose?

It spends most of its day eating white, but when it’s quick enough, it gets to eat fruit and sometimes some blue things. It’s in a dark room, where the walls are blue, it runs from a ghost that roams the halls and haunts it all the time. What is it?

How can one talk without saying a single word?

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