What does this rebus riddle means ?

A kind heart person buy packed food at 3$/packet from United states and sells them at 1$/packet at Africa. After some time he becomes a millionaire.

How come the guy become millionaire ?

Count the number of balls in picture below:

Complete the series by replacing "?" with the correct number.

ST ND RD TH '?'

I was born in a small house and I live in it all alone. No windows and no doors have been assigned to my house. The only way I can go out is by breaking through the walls of my house.

Who am I?

This is a simple one. You just have to count the number of Fs in the given sentence.

Finished Files are the result of years of scientific study combined with the experience of years.

How many did you count?

You are given a cube that is made with the help of 10x10x10 smaller cubes summing up to a total of 1000 smaller cubes. You are asked to take off one layer of the cubes.
How many remain now?

Which is faster, Heat or Cold ? Explain.

A word I know has six letters it contains, remove one letter and 12 remain. What is it?

When we see 2 but call 10?