Is this a true statement?

Question

Polynomials and radical expressions differ because radical expressions contain rational numbers as exponents and polynomials do not.

Answer 1

I think you have it backwards, with some additonal miconceptions.
Polynomials have rational (and, in fact, integer) exponents.

Radical expressions contain variables to fractional powers. A square root corresponds to an exponent of 1/2. That is still a rational number.