Which of the following statements are correct at 25 °C?

$K_a$or $K_b$of ${\mathrm{H}}_2\mathrm{O}=\frac{{10}^{-14}}{\frac{1000}{18}}$

$\Rightarrow p{K}_a$ of ${\mathrm{H}}_2\mathrm{O}=15.74\Rightarrow p{K}_b\left({\mathrm{OH}}^{-}\right)=-1.74$

or $p{K}_b$of ${\mathrm{H}}_2\mathrm{O}=15.74\Rightarrow p{K}_a\left({\mathrm{H}}_3{\mathrm{O}}^{+}\right)=-1.74$

$c\cdot \alpha ={10}^{-7}$ for water

$\Rightarrow \alpha =\frac{{10}^{-7}}{\frac{1000}{18}}=18\times {10}^{-10}$or $1.8\times {10}^{-7}\mathrm{\%}$