Answer :
[tex]It \ is\ rational\ number\ because\ we\ can\ write\ it\ as\ a\ quotient\ of\\two\ numbers:\\\\ \sqrt{0,25}=0,5=\frac{5}{10}=\frac{1}{5}[/tex]
[tex]\sqrt{0.25}\ is\ a\ rational\ number\ because\ \sqrt{0.25}=\sqrt{0.5^2}=0.5\in\mathbb{Q}[/tex]