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