Rational numbers cannot C. Be square roots of non-perfect squares.
Rational numbers are numbers that can be expressed as the fraction of two integers (where the denominator is not zero). The square root of a non-perfect square (like √2 or √3) is an irrational number, which means it cannot be expressed as a fraction of two integers.
The other options can either be true or false for rational numbers:
- A. Rational numbers can be represented as decimals that terminate or repeat infinitely, but they don't go on forever without repeating.
- B. Rational numbers can indeed be negative (e.g., -1/2).
- D. Rational numbers can repeat digits in their decimal representation (e.g., 1/3 = 0.333...).
Thus, the correct choice is C.