Solutions P, Q, R and S have the following properties:
P: pH 8
Q: [H+ ] = 1 x 10-3 mol/L
R: pH = 5
S: [H+ ] = 2 x 10-7 mol/L
When these solutions are arranged in order of decreasing acidity (most acidic first), the correct order is
Select one:
R, P, Q, S
P, S, R, Q
S, R, P, Q
Q, R, S, P