`10^(-6)`M HCl solution when diluted by 100 times, should become `10^(-8)` M solution. Then the pH value should increase from 6 to 8. However, a solution having pH value of 6 is acidic and the solution having pH value of 8 indicates basic nature. An acidic solution can never become neutral or basic howsoever dilute it is. The pH value of the solution is slightly less than 7. This is because in very low concentrated solution, the dissociation of water also should be taken into consideration. `H^(+)` ion concentration should be equal to the sum of `H^(+)` ion concentration from HCl and `H_(2)O`
`[H^(+)] " from " HCl = 10^(-8)`
`[H^(+)] " from " H_(2)O = 10^(-7)`
`[H^(+)] = 10^(-8) + 10^(-7) = 10^(-7) (10^(-1) + 1) = 1.1 xx 10^(-7)`
`pH = -"log" (1.1 xx 10^(-7))`
`= 7 - " log " 1.1 = 7 - 0.041 = 6.96`
