An American nightclub called 'The Coconut Grove' had a terrible fire in which over 400 people died. A simple design flaw in the building led to a high death toll. Subsequently, regulations were changed to ensure that all public buildings throughout the country eliminated this one detail, which proved deadly. What was it?

What is both possible and impossible at the same time?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

It has a long neck, A name of a bird, Feeds on cargo of ships, It's not alive,

What is it?

In which direction should the missing arrow point?

Which letter of the alphabet has the most water?

Can you quickly find which two matchstick figures are identical?

A boy was locked in a room by some robbers. All that is in the room is a piano, a calendar, and a bed. The room is locked from the outside. What does he eat, drink, and how does he escape and get out?

For an extra income, John decided to work at a Hotel for one hour daily. The manager offers him that they will pay him $11 after every 11 days.
However, John offered a different proposition to the manager. The offers stand as:
He will be paid just a penny on his first day.
Two pence will be paid on the second day,
Four pence will be paid on the third day.
And so on till the 11th day.

Should the Hotel manager accept his offer?

If it took eight men ten hours to build a wall, how long would it take four men to build it?