Aradical whose radicand is not a perfect power is a rational number

1. always
2. sometimes
3. never true

A perfect power is a positive integer that can be expressed as an integer power of another positive integer.
More formally, n is a perfect power if there exist natural numbers m > 1, and k > 1 such that .

Sometimes, some fractional or decimal radicants are not perfect power, yet they evaluate to a terminating decimal or recalling decimal.

Example: 6.25 is not a perfect power, but .

Therefore, A radical whose radicand is not a perfect power is a rational number SOMETIMES.

 3. Never true

Explanation
A radical number is of the form

where x s the radicand.

If x is of the form Mⁿ, where M is an integer, then the expression yields a rational number.
According to the question, the radicand is not a perfect power.
Therefore the expression cannot be a radical number.
 

A. is the answer in this question