What does the below image rebus riddle means ?

Here is a mathematical expression that also secretly tells a movie name. What movie is that?

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 arrange four 9's and use at most 2 math symbols, to make the total 100?

A chicken farmer has figured out that a hen and a half can lay an egg and a half in a day and a half. How many hens does the farmer need to produce one dozen eggs in six days?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

What has a ring but no finger?

What number do you get when you multiply all of the numbers on a telephone's number pad?

You are confined in a room and given two metal rods. Out of these two rods, one is magnet and the other is the iron rod. They look starkly similar. You don't have any other metal object in the room.

How will you decide which one of those is magnet?