1. Classify the following numbers as rational or irrational:(ii)     $\left ( 3+\sqrt{23} \right )-\sqrt{23}$

Given number is  $\left ( 3+\sqrt{23} \right )-\sqrt{23}$
$\Rightarrow \left ( 3+\sqrt{23} \right )-\sqrt{23} = 3+\sqrt{23}-\sqrt{23} = 3$
Now, it is clearly a rational number because we can represent it in the form of  $\frac{p}{q}$