For pure water at   ${50}^{\circ }$C, ionic product of water is ${10}^{-13}{M}^2$  and density of water is 0.9 g/mL. Select the correct options for $H_{2}O$  at  ${50}^{\circ }$  C:

any aqueous solution with pH = 6.7 is acidic

degree of dissociation of this water is  $2\sqrt{10}\times {10}^{-8}$

$pOH$ of this water is 7

dissociation constant $\left(K_a\right)$  of this water is  $2\times {10}^{-15}$