To rewrite \( \sqrt[4]{23} \) using a rational number as an exponent, we need to express the fourth root in terms of exponentiation.
The fourth root of a number can be written as that number raised to the power of \( \frac{1}{4} \). Therefore, we can express \( \sqrt[4]{23} \) as:
\[ 23^{\frac{1}{4}} \]
So the rational number that could be used as an exponent to rewrite \( \sqrt[4]{23} \) is \( \frac{1}{4} \).