Answer the following questions related to the basic sets of numbers on the real line:
a. (a) Define a rational number and an irrational number.
b. (b) State the characteristic of the decimal expansion of a rational number.
c. (c) Write one example of:
(i) a rational number with terminating decimal expansion,
(ii) a rational number with non-terminating but repeating decimal expansion,
(iii) an irrational number.