Answer the following questions related to rational and irrational numbers.
a. (i) Explain the main difference between a rational number and an irrational number with reference to their decimal expansions.
b. (ii) Justify whether 25 is a rational number.
c. (iii) Give a clear reason to show that 3 is not a rational number.
d. (iv) A student claims that 0.142857 is an irrational number. Do you agree? Give reason for your answer.