Select all irrational numbers.

√1/4

√2/4

√3/4

√4/4

√5/4

All but √4/4 are irrational because the definition of an irrational number is a number that is never ending like pi, or a number that cannot be converted to a fraction. √1/4 is irrational because when you find the square root, it comes out with a number that is near impossible to convert to a fraction because it is a never ending decimal.