What is black when you buy it, red when you use it, and gray when you throw it away?

Twenty frogs are sitting on a log floating on the surface of a river. Two of them decide to jump off into the water.

How many frogs are there on the log at this moment?

Can you make the below equation true by using any three numbers from "1, 3, 5, 7, 9, 11, 13 and 15"?

( ) + ( ) + ( ) = 30

What demands an answer, but asks no questions

Why is it against the law for a man living in Delhi to be buried in Mumbai?

In the given figure, move three matchsticks so that the resulting figure contains two rectangles.

It's a 7-letter word.
If we remove 1 letter from it, it remains the same.
If we remove 2 letters from it, it remains the same.
If we remove 3 letters from it, it remains the same.
If we remove all the letters from it, still it remains the same.
What is it?

What has many keys but can’t open a single lock?

There is a movie name hidden in the picture that is attached with this question. Can you find out which movie is it?

A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.