# 5. Rationalise the denominators of the following:    (i)     $\frac{1}{\sqrt{7}}$

Given number is  $\frac{1}{\sqrt{7}}$
$\Rightarrow \frac{1}{\sqrt 7} = \frac{1}{\sqrt 7}\times \frac{\sqrt 7}{\sqrt 7 } = \frac{\sqrt7}{7}$
Therefore, the answer is  $\frac{\sqrt7}{7}$