Which one of the following is not true?

Real numbers is the set which includes both rational and irrational numbers.

∴ Rational numbers and Irrational numbers are 2 independent subsets of Real numbers. Hence every real number is not a rational number (since real numbers also consists of irrational numbers.)

Option (A) is correct because every natural number can be expressed in form (q≠0 i.e a rational number).

Option (C) is correct because every whole number can be expressed in form (q≠0 i.e a rational number).

Option (D) is correct because every integer can be expressed in form (q≠0 i.e a rational number).

Natural numbers ⊂ Whole numbers ⊂ Integers ⊂ Rational Numbers ⊂ Real numbers

Real numbers ⊃ (Rational numbers + Irrational numbers).

Hence, only option B is incorrect.