the real number system which of the following is an irrational number √27 or ñ or 0/25

The irrational number is √27.

In the real number system, an irrational number is a number that cannot be expressed as a fraction of two integers and its decimal representation continues indefinitely without repeating.

Based on this definition, the number √27 is an irrational number because it cannot be expressed as a fraction of two integers and its decimal representation continues indefinitely without repeating.

On the other hand, "ñ" is not a number, and 0/25 is equal to zero, which is a rational number since it can be expressed as a fraction.