If the [H+] of a solution is 6.8 x 10-9 mol/L the pH is

8.2

Explanation:

To solve this problem;

 The concentration of [H⁺]   = 6.8 x 10⁻⁹mol/L

So, we need to convert this to pH:

           pH  = -log [H⁺]

So;

          pH  = -log 6.8 x 10⁻⁹ = 8.2

answer: the figure is attached herewith.

step-by-step explanation:   we are given to sketch a unit circle and label the terminal points corresponding to

in the attached figure, we have drawn a unit circle, with centre at o(0,0) and radius 1 unit. we have labelled the points a, b, c, d and e corresponding to the angles below

∠aox = 60°,

∠box = 120°,

∠cox = 180°,

∠dox = 240°,

∠eox = 300°.

and the coordinates are a(0.5,1), b(-0.5,1), c(-1,0), d(-0.5,-1) and e(0.5,-1).

thus, the answer is complete.

answer; i believe that the correct answer is (a) potassium(k)