I have a clock(12-hour format) and both the needles of the clock overlap at 12:00.
After how much time, they will overlap again?

I look flat, but I am deep. Hidden realms I shelter. Lives I take, but the food I offer. At times I am beautiful. I can be calm, angry, and turbulent. I have no heart but offer pleasure as well as death. No man can own me, yet I encompass what all men must have. What am I?

I am the beginning of the end, and the end of time and space. I am essential to creation, and I surround every place. What am I?

I am taken from a mine and shut up in a wooden case, from which I am never released, and yet I am used by almost every person. What am I?

I have an eye but still cannot see.

Who am I?

The more you take me, the more you leave me behind.
Who Am I?

How can you write nineteen in a manner that if we take out one, it becomes twenty?

The Puzzle: A girl, a boy, and a dog start walking down a road.

They start at the same time, from the same point, in the same direction.

The boy walks at 5 km/h, the girl at 6 km/h.

The dog runs from boy to girl and back again with a constant speed of 10 km/h. The dog does not slow down on the turn.
How far does the dog travel in 1 hour?

What breaks yet never falls, and what falls yet never breaks?

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?