True or False.

(1) f (x) = 2x is onto where f: R -> R. (Note: R is the set of real numbers)

(2) f (x) = 2x is one-to-one where f: R -> R.

(3) f(x) = x is onto where f: R -> R.

(4) f(x) = x is one-to-one where f: R -> R.

(5) f(x) = x is onto where f: R -> [0, ).

(6) f(x) = x is one-to-one where f: R -> [0, )