What are the smallest and the greatest rational numbers

Answer :

We know Rational number can be expressed in the form of $\frac{p}{q}$ , Where q $\ne$0 .   So ,

We can say that smallest rational number  = -$\infty$
And
Greatest rational number  = $\infty$

As we take $\infty$ is a rational number ( $\infty$ = infinity )