No. They can be positive or negative, depending on which perspective you have. So 3 - 2 is 1 whereas 2 - 3 is -1.
No.
No, it is not true.
no
No.
Yes, it is.
Not only could they be, but they always are.
Most of the time yes, positive or negative whole numbers count as rational numbers. So do positive or negative fractions.
Yes. The rational numbers are a closed set with respect to subtraction.
Yes, that's true.
A terminating or repeating decimal is always rational. Whether it is positive or negative makes no difference. So the answer is no it is not always rational, such as -1/pi
Never.
No. 5 and 2 are real numbers. Their difference, 3, is a rational number.