Answer:
a) 1 x 10^-11 mol/L
b) 1 x 10^-6 mol/L
c) 1 x 10^-5 fewer H+ ions
Explanation
pH stands for Power of Hydrogen, the more acidic a substance is, the more H+ ions it has rendering the substance acidic. a pH of 1 means the concentration of H+ ions is 1 x 10^-1. A pH of 7 means the concentration of H+ ions is 1 x 10^-7 and so on.
10^-11 has 10^-5 more H+ ions than 10^-6
Hope this helps :)