A value of pH 7.0 indicates A. an zero hydrogen-ion concentration. B. the lowest hydrogen-ion concentration. C. the highest hydrogen-ion concentration. D. equal hydrogen and hydroxide-ion concentration.

The correct answer is D. equal hydrogen and hydroxide-ion concentration.

Explanation:

The pH indicates the alkalinity or acidity of a solution. The pH less than 7 are acidic (more H + ions) and greater than 7 are basic (less H + ions). A pH of 7 indicates a neutral solution, being the case of water.

The water dissociation constant (Kw) = 1e10-14 = (H +) (OH-), and with pH = 7.00, the concentration of H + = antilog -pH = antilog -7 = 1e10-7 is calculated. Thus using the formula of kw, we calculate the concentration of OH- that at pH = 7, 00 is equal to the concentration of H +:

Kw = (H +) (OH-)

1e10-14 = 1e10-7 (OH-)

(OH -) = 1e10-14 / 1e10-7 = 1e10-7