What always comes into a house through the keyhole?

In a jungle where there are no street lights or any other artificial source of lights, I notice a black snake crossing the road.
How did I get sight of the snake?

Two-person want to cross a river. Only one boat is present on the riverside that can carry only one person at a time.

However, they still manage to cross the river. How is it possible?

Can you think of any three-dimensional shape that comprises of exactly two surfaces?

Can you find the hidden mobile that is lost in the rug?

A rubber ball keeps on bouncing back to 2/3 of the height from which it is dropped. Can you calculate the fraction of its original height that the ball will bounce after it is dropped and it has bounced four times without any hindrance ?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

What has lots of eyes, but can’t see?

Can you identify the hidden rebus in the image below?

Why is a river so rich ?