#### Answer

$\left\{ -12,-6,-0.9,-\sqrt4,0,\dfrac{1}{8},6 \right\}$

#### Work Step by Step

$\bf{\text{Solution Outline:}}$ Use the definition of rational numbers.
$\bf{\text{Solution Details:}}$ Rational numbers are numbers which can be expressed as the ratio of two integers. These include integers, fractions, and non-terminating but repeating decimals. Hence, the rational numbers of the given set,
$
K=\left\{ -12,-6,-0.9,-\sqrt{7},-\sqrt4,0,\dfrac{1}{8}, \dfrac{\pi}{4},6,\sqrt{11} \right\}
$
are
\begin{array}{l}\require{cancel}
\left\{ -12,-6,-0.9,-\sqrt4,0,\dfrac{1}{8},6 \right\}
.\end{array}