Are all whole numbers a rational numbers

Yes, they sure are.  A rational number is any number that can be written
as a fraction.  A whole number can always be written as . ..

           (the number) / 1 .    <== a fraction

Also, here's another fact that I think is very useful, but for some reason
people don't talk about it much:

ANY number that you can completely write down on paper with digits ... and
a fraction bar or a decimal point if necessary ... is always a rational number.