John was working on a Chemical Mixture whose weight comprise 90% liquid and 10% solid. The total weight of the mixture is 20 pounds. After a while, John noticed that some of the liquid evaporated and now the liquid comprises just 50% of the weight.

What is the weight of the chemical mixture now?

A patient was diagnosed with some ailment. He was given five different tablets to take at night at an interval of 15 minutes.

How long will it take the patient to consume all the five tablets?

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

John went to meet his friend Jacob, but when he was about to reach the main gate, John notices that Jacob had a mighty dog who was fastened to the tree. The chain is long enough that it allows the dog to reach the main gate.

How can the John reach the main gate?

What building has the most stories?

It can't be seen, can't be felt, can't be heard, and can't be smelt.
It lies behind stars and under hills, And empty holes it fills.
It comes first and follows after, Ends life, and kills laughter.
What is it?

If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left?

I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?

Using eight eights and addition only, can you make 1000?

There was an aeroplane crash, every single person died, but two people survived. How is this possible?