In the graph given below, what does the slope of the line represent ?
 

On comparing $\mathrm{p}={\mathrm{K}}_{\mathrm{H}}$ x with equation of straight line viz   $\mathrm{y}=\mathrm{mx}+\mathrm{c}, \mathrm{m}={\mathrm{K}}_{\mathrm{H}}$(Here, m- slope of the line).
Thus, Henry's law constant is represented by the slope of the line.