From the equilibrium of water dissociation, kW is equal to the product of hydrogen ions and hydroxyl ions. The hydrogen ion concentration is 1x10^(-4). Hence, at 298 K, the hydroxyl ion concentration...
The concentration of HCl is 0.100 moles per litre (M)
0.250 M
I'm pretty sure it's 1x 10 -2M because it must equel 14 that is the highest it can go the total pH
pH= -log [H+] = -log [1] = 0